[CMoore711]

Thanks for the comments guys, very appreciated.

Like I mentioned there was really only the one thread from some non-cadillac forum posted with some information on doing this mod and making this work. Although helpful and gave me a place to start, as I went through the process I felt it was lacking some additional info/detail, so I just approached it with a “what info would have helped me more before starting on this?” type of approach to my thread and pics.

Thanks for the informative post, it will help the V community for sure. The car looks great.

Appreciate it, and that was the exact intent.

Very nice write up. Looks great. How would this compare to using Coupe wheels and just make them 1/2 wider? They are already set out one inch further on the outside.

Very good question and after crunching some numbers this morning I feel it may be doable with coupe rear rims. I find this website here quite helpful when it comes to wheel/tire fitment Custom rims, wheel tire packages for your ride - RIMSnTIRES.com . I’m more of a visual learner (hence all the pics) and the explanation of rim offset and back spacing is one best done with pictures…

This is a screen shot from the visual comparison you can generate from the rimsntires link above, I kept the tire sizes the same for purpose of only showing how altering the rim specs changes things because on this particular website altering the tire size only changes the diameter and tire section width dimension.



So on the left you have the OEM CTS-V Sedan front 19” x 9” rim with +51mm offset, back spacing is 179mm (7”). On the right you have that same rim after widening it to 19” x 11”. Now… When you have rims widened, it’s all on the back side of the rim, so when I added 2” to the 19” x 9” +51mm offset rim with 179mm (7”) backspacing I increased the backspacing by +2”. Which netted a rim that was now 19” x 11” +77mm offset with 230mm (9”) backspacing. These dimensions will work as displayed for all intended purposes but TECHNICALLY…
*1” = 25.4mm, 2” = 50.8mm, 179mm + 50.8mm = 229.8mm (website doesn’t provide decimals on backspacing dimension so I rounded 229.8mm up to 230mm.) 230mm = 9.05” TECHNICALLY…

So when you decrease the offset of a rim, you are pushing it out away from the inside of the wheel well/suspension and towards the end of the fender. So when all of us are adding wheel spacers we are affectively lowering the offset of the rim.



On the right we have the stock OEM CTS-V Sedan 19” x 9” rim, now widened to 19” x 11” with +77mm offset and 9” backspacing. On the left displays the effects of the added 20mm Adaptec Speedware slip-on spacer w/ built-in wheel studs. Affective rim dimensions are now 19” x 11” +57mm offset and 8.2” backspacing. So… If one wanted to have some custom rims made and didn’t want to run spacers and wanted to run 325/30/19’s on the rear of their sedan, based in this info I believe it could be achieved with a 19” x 11” +57mm offset rim.

Now let’s answer your question gotjuice… I realize you asked what would be different in adding ½” to coupe rears compared to this, but I’m going to show the difference in adding 1” to coupe rears because most tire mfg recommend a min. rim width of 11”-11.5” for 325/30/19 tire.



On the left is the OEM CTS-V Coupe 19” x 10” rim with +40 offset and 7.1” backspacing. On the right is the same rim with an added 1” on the back side of the rim netting rim dimensions of 19” x 11” +52mm offset and 8.1” backspacing. By adding a 5mm spacer to the 1" widened coupe rim you can change the affective dimensions to 19” x 11” +57mm offset and 8.2” backspacing which are the same specs of my set-up.

So I believe this could be done with coupe rears widened 1” to 19” x 11” and the use of a 5mm spacer.

Great informative post. Did you get any wrinkle or warp on the rear panel? Dark cars makes it a lot harder to hide when pulling the fenders . Was it hard t ok keep that kind of heat on it? How long did each fender take?

Great questions and concerns, and you’re very right, it’s hard to hide with a black car and any wrinkle or warping isn’t guaranteed to happen, but it can. Fenders are formable and can be stretched/pulled, but you can only do so much before another area has to give in order to accommodate how far you’re trying to stretch the fender.

If you're looking at your wheel on the car from the side of the vehicle and visualize your wheel as a clock, when you're rolling the fender lip it's easier to go from say 9 o'clock all the way to 3-4 o'clock on the fender. All cars vary and are different and depends on where the rear quarter panel meets the rear bumper cover and how close the door jams are towards the fender edge etc. Now when you're wanting to pull the fender out, say 2-3 8ths of an inch like I did, it's much more difficult to work the area all the way from 9 o'clock to 3-4 o'clock. The rear fenders on our cars start to get much more difficult to work as they get closer to the door jam of the rear passenger doors, there's less metal there between the fender edge and door jam, it's stiffer, takes a lot more force to shape, force I didn't want to apply in fear of causing any damage. So most of the area of the fender that is pulled is between 10 o'clock and 2 o'clock on the radius of the fender respectively.

I will tell you that visually and even up close it is a challenge to see any imperfections, if at all. A lot of my pics are very up close and show many different angles of the rear fender lips and nothings noticeable. But if you run your fingers across the area that I pulled, it isn’t a 110% consistant arch, you may feel a slight 1-2 degree change in angle of the fender lip (1-3/8" area I detail in original post). A couple of my pictures show where the pull begins, and it's not very noticeable looking straight at the fender, but these two angles show it slightly. I've added some arrows to point it out.



The good thing is, I made it so that it is consistent on BOTH sides, so that it seems more as though it "belongs".


This is the area that is close to where the door jam for the rear doors of the sedan starts to get close to the fender opening, as the fender opening approaches the rear door jam the fender/panel area becomes less to work with and is also a lot stiffer. Additionally, when you're pulling a fender the pull has got to start and stop somewhere, you're not going to be able to pull the entire radius of the fender and not cause a potentially severe wrinkle or warp further up in the quarter panel. Unless you're already planning on doing some additional body work and painting.

It wasn't too hard to keep the heat on it, I think the heat gun I was using was 1500 watts, took about 20 mins of waving the heat gun along the fender about 4"-6" away from the surface to get up to temp, then as I worked the arm of the roller back and forth I did so with one hand and held the heat gun in the other hand and followed the roller as it moved back and forth.

All in all I'd say I have about 3-4 hours of just fender rolling/pulling work on each rear fender, this does not include the time for rivets, grinding/painting the lower spring seat lip, or grinding/painting the lower trailing arm.

I tried to take a few more pics today with some better lighting to really show the view of the meatiness from behind:




Thanks again for all the comments and feedback, and as Rich_J said, it's a lot of work but worth it in the end.

 

[TriTexan]

This will be quite the “TriTexan” post with plenty of detail and pictures...(bustin’ your
chops Tri, enjoy your posts and detailed input brother).

Hey man - I LOVE this stuff and don't mind a little ribbing! I know who I am and what I bring to the table - both good
and bad. And it's good to have you guys push me for brevity...there's a lot of value in being concise and I certainly don't
always achieve that.

But your post is totally appropriate - guys will get a TON of value from this nicely done write-up.

Inside I wasn’t touching anything but I was still VERY close to the fender liner, the lip of the lower spring seat, and the rear trailing arm. So for good measure I riveted the fenders similarly to the old thread referenced in the beginning of this post, and went at the lower spring perch and trailing arm with a die grinder, literally only “kissing” them to give me maybe 1-2mm of “just-in-case” clearance.

I wasn’t worried at all about shaving the trailing arm a bit, but the lip of the Lower Spring Seat is a bit of a sensitive area I feel, I initially wasn’t comfortable with touching it, but I had some conversations with a gentlemen who works at my local Tire Discounters who daily drives a V1, and has a C5 ZO6 he tracks. He shared with me that he has a close friend who tracks his V2 coupe and he informed me that they actually notched an “L” shape into his lower spring seat lip, some 5mm deep for inside wheel clearance and he has been beating that car on the track since with no issues. I was also in the company of some great mechanic friends, with welding and machining experience that inspected the areas of contact and what needed to be done very thoroughly and they were confident the 1-2mm window was not going to harm anything. That may not be enough confidence for some of you, but it was enough for me so we moved forward.

First - I don't think you have taken too much metal or strength away anywere - all of these OEM parts have a fair amount of safety margin built in. But I do have a suggestion - you should get a micrometer caliper or similar device and measure the thickness of unmodified pieces versus your post-mod sizes.

With these measurements we can do two things:

First, we can quantify exactly what "kissing" the part means so others can reproduce your results exactly. With one or two more people going thru this process and making their own measurements, we should be able to know exactly how much to shave off for very consisten results. Measuring two or three cars before and after the shaving should tell us a pretty good average or range of thickness to target with the grinding.

The second thing is we can get a much better idea of how much strength may have been lost. Certainly there are some metalurgists or materials engineers that can give us some more scientific feedback on what the net effect of your mods have done and whether it would matter in the real world.

Now I think you guys will find this quite interesting, and I wish I would have paid more attention to how I took the pics of the rims on the weight scale to be more identifiable as the new widened rear rims compared to the 19” x 9.5” oem sedan rear rim is in fact lighter. But holding a 19” diameter rim on a bathroom scale while trying to take a pic is a bit challenging. But pay attention to the rim that weighs 26 lbs. which is the oem sedan rear 19” x 9.5”, if you look closely that exterior lip of the inside barrel of the rim is the stock lip of the 19” x 9.5” sedan rear rim. Compare that to how different the new lips of Eric Vaughn’s widened 19” x 11” rims are and you know it’s not the same. That’s the only identifier I can clarify for you because most of you won’t want to believe this but… The stock CTS-V Sedan Polished rear 19” x 9.5” rim weighs 26 lbs. and the stock CTS-V sedan front 19” x 9”, now mind you just been widened to 19” x 11” weighed in at 23.2 lbs. AFTER IT WAS WIDENED to 11”.

The only thing I can think of is Eric Vaughn uses top notch materials and must use very high quality rim barrels for his widening work. I think it is also a testament to the caliber of his work.

I think the difference here is in how the hub area is constructed differently between the front and rear OEM wheels. The rears have a very short spoke offset while the front wheels the spokes are offset much further, presumably for brake clearance. This net effect of this is that if you look carefully at the pad material where the wheel contacts the rotor hat area, the amount of metal is different. I wonder what the result would be if you weight everything that is technically part of the wheel, including any spacers and such...but either way, you definitely point out a curious factoid. Does it matter? I think so - 3 lbs seems like a LOT of unsprung weight to me. But it is probably the least of your worries if you are taking on a challenge like this. The goal is fat tires on OEM-looking wheels.

This certainly isn’t the first time this has ever been done on a sedan, in fact this thread here was posted some time ago with some insight and a bit of “how to” and it certainly gave me enough “it can be done” motivation to do take this little project on.

So I have a set of custom Forgelines with 20x9.5 inch fronts and 20x11.0 inch rears. I am running a 305/30/20 Pilot Super Sport rear tire. My fronts are 275/35/20 Super Sports. My fronts seem to have plenty of clearance, but I have seen some tiny witness marks on the right front that looks like the wheel or tire has rubbed a bit - it's at the top and I apologize but I don't know the correct name of the suspension part I am talking about and I don't have a pic handy...but it's the big cast peice that goes from over the top of the tire down to the steering pivot point...the wheel/tire rubs on the inside of this ever so slightly...

On the rear, I have 11.0 inch rears also, but ZERO suspension or fender mods. The wheels and tires offer plenty of clearance with the suspension compressed. I have all alignment set to factory specs, too. The alignment guy at the local dealership, who has been doing alignment and suspension work exclusively for Caddy for 35 years, says I have plenty of clearance as the suspension compresses further.

In the rear, I DO have rubbing in two specific areas. First if the frame just in front of the rear wheel. When the suspension lowers (while on a lift using the car's frame, for example), I get some clear contact there between the tire and the frame. I think I might need 2mm more clearance to eliminate that.

The other place I have rubbing is between the rim protection bead on the MPSS, which is HUGE, and the plastic shock dust boot. Again, this only occurs when the suspension is fully extended. Once on the ground, there's a good half inch.

So my question is - if I am running 9.5 fronts and 11.0 inch rears with NO suspension parts modified front or rear, I'm thinking the main difference between my setup and this one is the 19 inch diameter that causes additional clearance issues with the suspension parts, mainly in the rear - correct?

I have my stock polished sedan rims for my OBM wagon that I would LOVE to widen and do this exact same process with. My 20's are nice, but they ride much harsher than the OEM's. If I could get this tire combo, it is plenty close enough to stock diameter for me and would give me a little more complaince on the sidewall...unless the RE-11's are just WAY harsher than the PS/2's.

I gotta say - this is an AMAZING post and great documentation and discussion. THIS RIGHT HERE is the core value that a forum like this brings to a car enthusiast group.

I may undertake this same mod for my OEM wheels (perhaps without refinishing even) and use this process and see what improvements we can make. I'd definitely want to collaborate with someone who's gone there before.

Well done! I'm thinking in addition to VOTM, we should have some kind of award for amazing mods like this. Mod of the month? And THAT is where the $100 should go IMHO...

 

[TriTexan]

I also just noticed that you can get the Michelin Pilot Super Sports in these same sizes, as well as the Goodyear Eagle F1 Supercar (rubbish tires IMHO...) as well as the Hankook Ventus V12 Evo2 - a popular CTS-V tire option in stock and 20 inch sizes.


FWIW, I am looking at the tire specs for some additional comparisons. What I am finding is interesting as well. For example, Tirerack.com and/or the respective manufaturer's website lists additional dimension information, including section width and tread width.

The tread width on my MPSS 305/30/20 rear is 11.8 inches and the section width is 12.3 inches. On the RE-11's in 325/30/19 size, the tread is 11.5 inches and the section width is 13 inches on a measuring rim of 11.5 inches. Reduced down to an 11 inch wide rim and the section width would be about .5 inches less as well, or about 12.5 inches. I say that because the specs for the RE-11 are listed for an 11.5 inch wheel, not 11. General rule of thumb is that if you go up or down in wheel width, the section width changes by about the same amount (within reason), but the tread width is unaffected...

SO - what it comes down to is that a Michelin Pilot Super Sport in 305/30/20 inch size has a little more tread width than a 325/30/19 RE-11 and is a tad narrower in section width with both mounted on an 11 inch wide wheel. I find it intriguing that these two tire size combinations, while totally different in size naming convention, turn out to have very similar road contact and sidewall width dimensions. That's a GOOD thing in my view though. We like to have options for our V's!

Where I am going with all of this is just to ensure we all know the measurements and specs involved here and what they mean, how that affects contact patch, and so on. I was really thinking that a 325 rear and 285 front would be and incredible setup on the stock 19 inch diameter. What I am realizing as I dig a little deeper is that the contact patch I have with my 275/35 and 305/30's on my 20's are roughly going to be the same as a conventional 285 front 325 rear set of tires on 19's.

Too many people get caught up on the numbers and miss the reality. Just because your tire says "345" on the side doesn't mean it's bigger, better, or wider than a 325 from another manufacturer. Those numbers DO mean something, but for us V drivers, ultimately what we care about is grip, right? And we know contact patch is somewhat of a proxy for grip. Just don't fall into the trap of thinking those sidewall numbers tell you the whole story - they don't...

So my last question would be - would everything still work OK with the Pilot Super Sports instead of the RE-11's? And if so, why did you go with the RE-11's in this case? Just curious what your thought process was - cost, grip, recommendation by other forum members, etc etc.

I will tell you - I am in love with the MPSS...it is by far the perfect all-around DD tire and still has pretty good grip even with my mods. It's definitely not a DR, but it's amazing in ALL categories. I would love to follow your process with this widening and do a set of MPSS tires on this configuration. I bet it would ride and grip way better than stock, but still LOOK very stock.

Dude - thanks for getting me all worked up! I thought I was done modding for a while but NOOOOOO....YOU had to stick this thread out there and get my juices flowing for MORE MORE MORE. Oh well - I guess that's the life we lead right?

 

[Trevorlj]

Awesome work!

Here's a 325/30/19 PSS:

 

[TriTexan]

Awesome work!

Here's a 305/30/19 PSS:

FAT!!!!

From Tap uh talk

 

[CMoore711]

First - I don't think you have taken too much metal or strength away anywere - all of these OEM parts have a fair amount of safety margin built in. But I do have a suggestion - you should get a micrometer caliper or similar device and measure the thickness of unmodified pieces versus your post-mod sizes.

With these measurements we can do two things:

First, we can quantify exactly what "kissing" the part means so others can reproduce your results exactly. With one or two more people going thru this process and making their own measurements, we should be able to know exactly how much to shave off for very consistent results. Measuring two or three cars before and after the shaving should tell us a pretty good average or range of thickness to target with the grinding.

The second thing is we can get a much better idea of how much strength may have been lost. Certainly there are some metalurgists or materials engineers that can give us some more scientific feedback on what the net effect of your mods have done and whether it would matter in the real world.

I’m comfortable with the minimal amount of shaving we did to accomplish the additional clearance needed to make it work. Measuring the amount we actually did shave with some calipers is a great idea, and my buddy even has a set of digital micrometer calipers! I should have done that. Maybe if I have time I’ll get back there and remove the wheels and take some spot measurements of my post-mod dimensions.

So I have a set of custom Forgelines with 20x9.5 inch fronts and 20x11.0 inch rears. I am running a 305/30/20 Pilot Super Sport rear tire. My fronts are 275/35/20 Super Sports. My fronts seem to have plenty of clearance, but I have seen some tiny witness marks on the right front that looks like the wheel or tire has rubbed a bit - it's at the top and I apologize but I don't know the correct name of the suspension part I am talking about and I don't have a pic handy...but it's the big cast peice that goes from over the top of the tire down to the steering pivot point...the wheel/tire rubs on the inside of this ever so slightly...

On the rear, I have 11.0 inch rears also, but ZERO suspension or fender mods. The wheels and tires offer plenty of clearance with the suspension compressed. I have all alignment set to factory specs, too. The alignment guy at the local dealership, who has been doing alignment and suspension work exclusively for Caddy for 35 years, says I have plenty of clearance as the suspension compresses further.

In the rear, I DO have rubbing in two specific areas. First if the frame just in front of the rear wheel. When the suspension lowers (while on a lift using the car's frame, for example), I get some clear contact there between the tire and the frame. I think I might need 2mm more clearance to eliminate that.

The other place I have rubbing is between the rim protection bead on the MPSS, which is HUGE, and the plastic shock dust boot. Again, this only occurs when the suspension is fully extended. Once on the ground, there's a good half inch.

So my question is - if I am running 9.5 fronts and 11.0 inch rears with NO suspension parts modified front or rear, I'm thinking the main difference between my setup and this one is the 19 inch diameter that causes additional clearance issues with the suspension parts, mainly in the rear - correct?

You are absolutely right, 20” vs. 19” rims is like adding a little Mio or adding a lot, it changes EVERYTHING. I’m sure Forgeline has calculated some different offsets then what I have going on as well. Which a couple mm here and couple mm there doesn’t seem like a lot, but when you’re trying to maximize what space is there and we’re dealing with offsets and backspacing, it’s a millimeter game of fitting right or not. Lifts are great and make working on cars so much easier, but one thing that seems is very hard to be able to do is to compress the suspension while the car is on a lift and still safely be in a position under the car to be able to examine how close you’re wheels are getting to what body/suspension parts.

*I love your Forgelines BTW, they’re a great company and I have a good mechanic friend who has some close contacts there. Their facilities are in fact 25-30 mins from where I live. If ever decide to drop that kind of coin on rims, they’ll be Forgelines for sure.

I gotta say - this is an AMAZING post and great documentation and discussion. THIS RIGHT HERE is the core value that a forum like this brings to a car enthusiast group.

I may undertake this same mod for my OEM wheels (perhaps without refinishing even) and use this process and see what improvements we can make. I'd definitely want to collaborate with someone who's gone there before.

Well done! I'm thinking in addition to VOTM, we should have some kind of award for amazing mods like this. Mod of the month? And THAT is where the $100 should go IMHO...

Thanks Tri I appreciate the comments, between you and msydow I think you guys are onto something with this VOTM and $100!

The tread width on my MPSS 305/30/20 rear is 11.8 inches and the section width is 12.3 inches. On the RE-11's in 325/30/19 size, the tread is 11.5 inches and the section width is 13 inches on a measuring rim of 11.5 inches. Reduced down to an 11 inch wide rim and the section width would be about .5 inches less as well, or about 12.5 inches. I say that because the specs for the RE-11 are listed for an 11.5 inch wheel, not 11. General rule of thumb is that if you go up or down in wheel width, the section width changes by about the same amount (within reason), but the tread width is unaffected...

SO - what it comes down to is that a Michelin Pilot Super Sport in 305/30/20 inch size has a little more tread width than a 325/30/19 RE-11 and is a tad narrower in section width with both mounted on an 11 inch wide wheel. I find it intriguing that these two tire size combinations, while totally different in size naming convention, turn out to have very similar road contact and sidewall width dimensions. That's a GOOD thing in my view though. We like to have options for our V's!

Where I am going with all of this is just to ensure we all know the measurements and specs involved here and what they mean, how that affects contact patch, and so on. I was really thinking that a 325 rear and 285 front would be and incredible setup on the stock 19 inch diameter. What I am realizing as I dig a little deeper is that the contact patch I have with my 275/35 and 305/30's on my 20's are roughly going to be the same as a conventional 285 front 325 rear set of tires on 19's.

Too many people get caught up on the numbers and miss the reality. Just because your tire says "345" on the side doesn't mean it's bigger, better, or wider than a 325 from another manufacturer. Those numbers DO mean something, but for us V drivers, ultimately what we care about is grip, right? And we know contact patch is somewhat of a proxy for grip. Just don't fall into the trap of thinking those sidewall numbers tell you the whole story - they don't...

Yes it is known that even though referenced size format in regards to tires is universal, the actual tire dimensions can and will vary between manufacturers. The MPSS do run wide, VERY wide.

MPSS 325/30/19
Measuring Rim: 11.5”
Section Width: 13”
Tread Width: 12.5”

Bridgestone RE-11 325/30/19
Measuring Rim: 11.5”
Section Width: 13”
Tread Width 11.5”

I’m thinking they include that rim protector bead in their tread width dimension because that’s about how big that thing is, ½” on each side. I’m just kidding, but that rim protector bead is serious. But an additional 1” width of tread while still maintaining the same Section Width is very interesting. If both section widths are the same, where’s the extra 1” of tread width on the MPSS? Does it round the corner of the tire and go more into the sidewall than the RE-11 in the same size? I think someone would have to take an RE-11 and MPSS in the same size and mount them on the exact same sized rim and take some physical measurements to really find out.

So my last question would be - would everything still work OK with the Pilot Super Sports instead of the RE-11's? And if so, why did you go with the RE-11's in this case? Just curious what your thought process was - cost, grip, recommendation by other forum members, etc etc.

I will tell you - I am in love with the MPSS...it is by far the perfect all-around DD tire and still has pretty good grip even with my mods. It's definitely not a DR, but it's amazing in ALL categories. I would love to follow your process with this widening and do a set of MPSS tires on this configuration. I bet it would ride and grip way better than stock, but still LOOK very stock.

Dude - thanks for getting me all worked up! I thought I was done modding for a while but NOOOOOO....YOU had to stick this thread out there and get my juices flowing for MORE MORE MORE. Oh well - I guess that's the life we lead right?

Glad I could get the wheels in your head turning some more mod ideas…

Would everything work ok doing this mod with the same corresponding tire sizes in MPSS’s, I would say yes, but would there maybe be even more additional or different locations of clearancing steps needed to do so, possibly… Based on my experience with tires I think I would make the same statement with any other brand 325/30/19 other than the Bridgestone RE-11’s. Now we’re not talking about EXTREME differences, but there could be some.

I purchased the vehicle used privately with 305/30/19 RE-11’s on the rear stock rims already, and the stock 255/40/19 PS2’s up front, that were more warn than the rears. So it wasn’t long before I installed matching 265/35/19 RE-11’s up front. The RE-11’s are excellent tires, you speak very highly of the MPSS in many threads and the way you speak of your experiences with the MPSS is identical to my experiences with the RE-11’s to the T. I am completely impressed with their dry traction and even more so amazed at how they perform in the wet, like serious rain cruising down the highway at decent speeds and not once felt the car hydroplane. In fact I kept pushing the car on the highway despite the rain just to test the tires wet traction limits, and I was uncomfortable at the speeds given the rain and wet road conditions before the tires were. I’m also impressed with the way they wear, my 305/30/19 rear tires were shot when I removed my stock rims (since I purchased the car used with the 305/30/19 RE-11’s already on there I’m not exactly sure at what mileage they were put on) but my front 265/35/19 RE-11’s were still in great shape, they had just shy of 10K miles on them and I spot measured them with a tire tread depth reader and the inside of the tire still had 6-7/32’s and the middle and outside of the tire had 7-8/32’s worth of tread. They come with 9/32 tread depth new, so just under 10K miles of driving that’s pretty good wear if you ask me, granted they’re the front tires and our V’s are RWD, but still tire wear is tire wear.

I picked up two 325/30/19 RE-11’s from tirerack about 2 months ago, at the time there were less than 10 left and they were on a sweet closeout deal of $338/ea. Which is almost $100 cheaper per tire than the MPSS’s, tirerack was shortly out of stock, and if you searched 325/30/19 the RE-11’s didn’t even come up as a corresponding match, because they didn’t have any. Today their website says they have less than two in stock. Since I was so impressed with the previous performance of my 305/30 & 265/35 RE-11 tire set-up I decided to stick with them, despite everyone’s rave reviews of the MPSS’s. Maybe once I burn through these I’ll give the MPSS’s a shot.

So I’ve been pushing the car a bit in the corners and under acceleration TRYING to get the tires to rub and so far so good. I say this because I’ve generated a bit of brake dust on the wheels and they still look great, more of a gunmetal look. Nowhere near as noticeably dirty as the stock polished finish, these PVD coatings for rims are where it’s at!

Oh Tri and you mentioned collaborating with someone who’s gone down that road should you try to embark on this mod project I’d be happy to help anyway I could. If anyone has any questions feel free to PM me.

In fact, I went ahead and purchased the EASTWOOD FENDER ROLLER TOOL, I’d be happy to rent it out to anyone interested for a small fee and deposit, I could rent the EASTWOOD FENDER ROLLER and a heat gun. PM me for details if you’re interested.

Trevorj - That 325/30/19 MPSS is meaty and looks appropriate for the size, someone would have to put them side-by-side to really do a compare, and even further mounted on identical size rims.

You and your coupe have it easy on mounting those bad boys!

 

[ShelteredV]

You get my vote! I wouldn't have the balls to this, I'd shit a brick when I fucked up and put a wrinkle in my quarter!

 

[vspec]

I just bought my car used and it had been modded. I went to the tire shop and then was informed there were spacers on the car. Im not exactly sure the size of them but I did see 11/15 on there. They look like 1/2" or slightly thinner. The car came with another set of rear wheels that are 19x10 so I am assuming they are from a coupe.

I am planning on black chroming a set. The question is: If I move the rear 19x9.5 to the front and the 19x10 on the rear, will they have they same stance as i have currently with the spacers? Will the wheels stick out of the fender?

 

[gotjuice?]

I just bought my car used and it had been modded. I went to the tire shop and then was informed there were spacers on the car. Im not exactly sure the size of them but I did see 11/15 on there. They look like 1/2" or slightly thinner. The car came with another set of rear wheels that are 19x10 so I am assuming they are from a coupe.

I am planning on black chroming a set. The question is: If I move the rear 19x9.5 to the front and the 19x10 on the rear, will they have they same stance as i have currently with the spacers? Will the wheels stick out of the fender?

No, Coupes are 10.5 and Sedans are 10 on the rear.

 

[CMoore711]

No, Coupes are 10.5 and Sedans are 10 on the rear.

This is not accurate...

Sedan & Wagon rims are 19" x 9.5" on rear, Coupes are 19" x 10" rear.

Vspec, search the forum for coupe rims on sedan and you should be able to find threads with pictures. IIRC the coupe rears do stick outside of the fender slightly, maybe <1/4", when mounted on rear of sedan. Some have put them on the rear of a sedan with the factory 285/35 rear size tire which is slightly stretched on the 10" rim and due to the tire stretch haven't had issues with fitment. So it depends on what size tires you're trying to run.

You will definately need a spacer for the front in order to mount the sedan 19" x 9.5" rear rim up front. This is due to the concave of the spokes on the face of the rim. They will not clear the stock front Brembos brakes without a spacer, most run 11mm up front, some have also used 15mm spacers up front.

 

[TriTexan]

I’m thinking they include that rim protector bead in their tread width dimension because that’s about how big that thing is, ½” on each side. I’m just kidding, but that rim protector bead is serious. But an additional 1” width of tread while still maintaining the same Section Width is very interesting. If both section widths are the same, where’s the extra 1” of tread width on the MPSS? Does it round the corner of the tire and go more into the sidewall than the RE-11 in the same size?

So I took a quick few measurements out in the garage to confirm whether or not Michelin was playing any games with us on "tread width". My initial take is that these measurements are reasonably honest to real life.

What I needed was a flexible fabric tape measure to get proper results. I used a rigid tape measure because that's what I had on hand. I could hold the tape measure with both hands and get a good measure, but then no hands left to take a pic. But I'll report my results and you'll have to trust me...

I wanted to get an honest measure of tread width. I wanted to capture the full tread width that would be engaged between a combination of cornering, braking, accelerating, and so on. As the car moves around, different parts of the tire and shoulder will come into contact with the ground. You can easily see the scuffed areas of the tread that represent this contact.

Below are some pictures - but first a recap and findings: I am running a MPSS 275/35/20 front and 305/30/20 rear and my Forgelines are the "recommended" rim width for both tires...9.5 wide front and 11.0 inch rear. So the measurements of my tires SHOULD match what Michelin claims.

MPSS 275/35/20:

Tread width - mfg claimed: 10.1
Tread width - measured: 10 1/8th (10.125)

Section width - mfg claimed: 10.9
Section width - measured: 11.0

MPSS 305/30/20:

Tread width - mfg claimed: 11.8
Tread width - measured: 11 3/4 (11.75)

Section width - mfg claimed: 12.3
Section width - measured: 12 3/8th (12.375)

So what I found is that the Michelin claimed tread width specs line up with real world measurements pretty well. Does that mean the contact patch is larger? Well not necessarily so. Look at the pictures below - note that my 275 front has significantly wider grooves in it than my 305 rear. I would expect this helps shed water better, but wider grooves also mean less rubber in contact with the ground. So don't be fooled into thinking that just because a Pilot Super Sport is an inch wider at the tread that your tire that it must have a bigger contact patch. That may or may not be true.

One thing is for sure though - you're gonna need a LOT more clearance on the sides with a Pilot Super Sport than most other makes of tire. But ask anyone who has driven a set of these on a properly set up wheel and suspension setup and they'll tell you - they're amazing all around tires. The drip grip on my 675 whp wagon in the dry is just incredible. The fact that every single stoplight doesn't result in a smoky burnout is proof that you don't HAVE to have drag radials to put down some decent power. And I can get on the throttle in the wet nearly as much as I can in the dry - which is as much scary as impressive. And they are quiet, wear nice and even, and last a hell of a lot longer than the factory PS/2's.

Ok - enough marketing by me for Michelin. But this shows me that the specs you read online are more or less accurate in the real world. But noticing the large gaps between the tread rings, I've realized that while the MPSS are indeed a lot wider tires for the same sidewall markings than comparable brands, it doesn't necessarily mean more rubber in contact with the ground. I suspect the MPSS does in fact have more contact, but that's just a lot harder to measure, and I just don't have time to work on that little project tonite LOL!

Hope you guys find this informative.

And I will definitely be taking my OEM polished stock wheels that I took off my wagon and converting them as done here into a 285 / 325 setup for the wagon if I can possibly pull that off. I would LOVE to see how the car rides and handles with that combination. I love my Forgelines and the 20's, but the ARE a lot rougher riding than the stock setup. Going back to a 19 would give me a little more sidewall, which would be good for both ride quality AND launch grip. And who knows....maybe I'll get frustrated and just have Forgeline make me a set of 19's to go with my 20's...

-=TT=-


Front 275 - note that I've lined up the tape measure so that the starting end of the tape is aligned with the inside edge of the tire right where scuffing shows it is making contact with the road. It just doesn't look like it in this picture!

Rear 305 - again, lined up with the scuff witness marks on the tread. And again it doesn't look quite right, but notice the spacing between the treads and how much narrower the grooves are...curious eh?

 

[CMoore711]

Since it seems more and more guys are pushing the limits of rim/tire fitment on their V's, I will be offering up my Eastwood Fender Roller & Heat gun tool for rent. Since rolling fenders is pretty much and one and done process and I sure wish there was one available for me to rent when I needed one versus all out buying the tool.

If interested feel free to PM me for details, if there is enough interest I may start a new thread for it.

I've already touched base with Tony on this and all is well. I'm not trying to become a site vendor or retire off renting out a fender roller. Just figured I'd throw it out there as an option for those in the V community interested in gaining that little more wheel well clearance for wide rim/tire set-ups.

 

[random84]

I'm keeping my wheels as long as the refund clears - so I might be taking you up on the roller. Any chance I can bribe you into lending me a hand if I drive up on a mutually convenient day?

Sent from my SCH-I545 using Tapatalk

 

[CMoore711]

I'm keeping my wheels as long as the refund clears - so I might be taking you up on the roller. Any chance I can bribe you into lending me a hand if I drive up on a mutually convenient day?

Sent from my SCH-I545 using Tapatalk

Sent you a PM.

 

[soon to V]

Just saw this. Fantastic information for sure. Came across it doing some research on how to get more "meat on the bone" since I do a lot of track days and autocross. I now plan to try 285 up front and 305 (on a 10.5 rim to be done by your guy mentioned), but before I pull the trigger, any new news to post regarding your work here? I will be putting my car through all the car has to give and I'm running D3 competition lowered springs. Just spent the afternoon under the car checking all the data and spacer needs but I can't do any dynamic testing and also can't see tire deformation shapes for interference et el. So, just thought I'd check to see how this set up is working for you. Oh, by the way, surprised you're right here in my Ohio area. Mike

 

[pepn3385]

He sold the car actually. This is an awesome mod though! Looks great!

 

[TriTexan]

Just saw this. Fantastic information for sure. Came across it doing some research on how to get more "meat on the bone" since I do a lot of track days and autocross. I now plan to try 285 up front and 305 (on a 10.5 rim to be done by your guy mentioned), but before I pull the trigger, any new news to post regarding your work here? I will be putting my car through all the car has to give and I'm running D3 competition lowered springs. Just spent the afternoon under the car checking all the data and spacer needs but I can't do any dynamic testing and also can't see tire deformation shapes for interference et el. So, just thought I'd check to see how this set up is working for you. Oh, by the way, surprised you're right here in my Ohio area. Mike

He sold the car actually. This is an awesome mod though! Looks great!

Another active forum member now owns the original car - he's online from time to time and I've PM'd him to see how he likes it - and so far he loves it. I forget his screen name but I could dig it up if someone needs it.

 

[CMoore711]

Just saw this. Fantastic information for sure. Came across it doing some research on how to get more "meat on the bone" since I do a lot of track days and autocross. I now plan to try 285 up front and 305 (on a 10.5 rim to be done by your guy mentioned), but before I pull the trigger, any new news to post regarding your work here? I will be putting my car through all the car has to give and I'm running D3 competition lowered springs. Just spent the afternoon under the car checking all the data and spacer needs but I can't do any dynamic testing and also can't see tire deformation shapes for interference et el. So, just thought I'd check to see how this set up is working for you. Oh, by the way, surprised you're right here in my Ohio area. Mike

The car is also lowered on D3 Comp Springs with this wheel/tire set-up. Although I didn't track the car I can say in my area there are plenty of "clover" style highway on and off ramps as well as some fun back roads that provide some <90 degree S turns that I would always push the limits on at varying speeds trying to get the tires to rub and they never did. Although it pained me, for a short while I would even purposefully try to go over certain bumps and inclines at various angles and speeds, still the tires never rubbed. One area around me specifically has a sharp turn at the bottom of a decent hill decline, which taken at a bit of speed would net a pretty good amount of compressed suspension while turning and I could never get the tires to rub on that corner.

I can tell you that after doing the fender work and having run the 325's for some time I would absolutely do this mod again, and do it all the same exact way I did it. I really think the 325/30/19 and 285/35/19 tire combo works very well, the overall tire diameters are so close to the stock tire size combo, just a lot wider. Everything is improved, steering response, turn-in, straight line traction, yet it still rides like a stock V lowered on stock wheels/tires, not a V lowered on shorter sidewall tires like the 265/35 and 305/30/19 set-up I had before doing the widening.

If I were tracking my V Sedan/Wagon on the road course, I would without a doubt do this mod. This is the way to maximize wheel well clearance and tire width without fully committing the money/time into a widebody kit.

Another active forum member now owns the original car - he's online from time to time and I've PM'd him to see how he likes it - and so far he loves it. I forget his screen name but I could dig it up if someone needs it.

I have since sold the car, in fact exactly 1 month ago today! I sold it exactly how it was in this thread, wheels and all. It now resides in the Virginia Beach area and the new owners screen name is Bgbsi06, his new member intro thread is here: http://www.ctsvowners.com/forum/2-new-member-introductions/24080-i-got-lucky.html

 

[soon to V]

Awesome. Great information to hear; Thanks all! Gives me confidence that maybe it will survive the hard fall off the oval onto the infield at Michigan International Speedway. For autocross, it should be a big help and I'm not concerned about that, just mostly that MIS dip, but we'll see. I am doing the 305's just so I don't have to roll the fender. I may try it after trying this, but taking one step at a time for now. Thanks again. Hope you are still driving something fun. Mike

 

[JD_SS]

Can I get a TLDR ?