HELP!! TREAD width vs SECTION width on Cup 2s

[Dinosgt]

Update - I am still struggling with finding someone who knows the answer regarding the AUDI vs the Porsche tire. I understand that the "R01" and "N01" specs are the compound and stiffness specs from the OEMs, but NO ONE can tell me (Tire rack, my vendor, local installers, etc.) if the Tread widths are the same (as Tire rack seems to believe).

I have written to Michelin and awaiting a response (hopefully).

Question for the collective wisdom - am I missing something? I have seen tons of guys running 305/30 and 305/35s in the rear, and the tires don't appear to stick out of the fenders. Did everyone go with an offset greater than 55mm? If so, were mods necessary to the inside fender cover/bump stop bracket?

THANKS...

 

[Steve@TF]

i replied to your pm.

your wheel offset is perfectly normal for these cars. its just that michillens run wide. as do toyos. ive put plenty of nitto 305s on gt500s and they look like theyre sticking out going to rub and people think theyre going to....and they dont. there are guys running 20s with less offset than your wheels and 315s without issues. with the Pro kit springs you will be fine. i can all but guarantee you will not rub. looks wise, well that is subjective. have you driven the car with the wheels/tires on yet? or are you just worried its going to rub.

if you were to use the same tire but drop to a 10.5" wheel, it would be worse. the wider the wheel is, the more stretched the tire is and you get more clearance. with the offset you have, you should not be affected by the bumpstop bracket, even at full droop. i dont think so anyways. your wheels are pretty much fender flush. if you were to push the wheels in more (add more offset) then yes they will hit at full droop. but only when the wheels are hanging in the air. not while driving. the solution? just jack the car up enough to get the wheel on/off. my own car does this lol. i havent relocated the brackets. im running 20x11 on 295 mpss with a few more mm offset then your wheels.

if the look of how it sits bugs you, call the wheel manufacturer and ask them if they can possibly shave some material off the backpads to bring the wheel in some. we do this all the time and depending how the wheels are cut, we can remove up to 5mm of material. anything less than 3mm is not really worth the effort of sending them back though. 3mm = .118" which should make you happy and not really that much material for them to remove. if theyre willing. that's the key.

the ONLY wheels i have personally seen where this can not be done are Alcoas due to the hub bore being tapered (weird). if you did, they would no longer be hub centric. (we actually discussed doing this lol).

how your car sits now, OR if you are able to remove a few mm off the backpad, will require no modifications to your car. *if somehow they can remove a whole 5mm off the back, then the tires themselves could possible rub on the inner fender wells during hard cornering, due to them being Mich.. i experienced that when i ran 19x11 with 325s.

no offense to you at all but i would have to say that i cant blame the company for the offset they used. that's a good offset. you cant expect them to know the widths/profiles of every different tire and every different car. i know because i own a gt500 and have done lots of experimenting. most companies use 51mm which is straight up flush. MOST mustang owners dont run wide tires. most use 275/285 and that offset makes the wheels/tires nice and flush. so they were actually a little conservative. they are probably afraid to go in any more in fear of running into something.

as i mentioned in my pm, a non-lowered car with a high offset wheel will run into rubbing problems. when you lower the car, it drops the bumpstop bracket below the rim. on a stock car, its right there. we've been putting wheels on gt500s since day 1 and yet we only found this out a few months ago lol. a customer order 20x11 with 315s for his bone stock gt500. they tires actually got stuck on the bracket, at ride height. the easy solution? just a slight drop solves the issue. the reason i mention this experience is to support my statement why companies are careful about putting too much offset on the wheels.

as far as your section width questions, i have no idea lol. as mentioned, there is no industry standard for measuring the width of a tire. i put a 315 nitto NT05 next to an mpss 295/35/20 and they were pretty much the same width. as far as contacting michelin, i wouldnt expect to get anywhere with that. theyre a BIG company. that's like trying to get ahold of a ford engineer to ask a specific question about your car. not to mention michelin is a french company making it even less likely to get ahold of anyone with any real knowledge on the subject.

hope that helps

 

[Pribilof]

Thanks to Steve for the great post.

As far as wheels / tires rubbing the bumpstop bracket... Just cut it off. Seriously. I was scared to cut out mine, until I actually did it. It's just some ugly ass piece o metal, takes 15 minutes to cut and paint. I've never don't anything like that before and my wheel wells look like they came like that from the factory

 

[Dinosgt]

i replied to your pm.

Many thanks Steve - pm replied to as well.

your wheel offset is perfectly normal for these cars. its just that michillens run wide. as do toyos. ive put plenty of nitto 305s on gt500s and they look like theyre sticking out going to rub and people think theyre going to....and they dont. there are guys running 20s with less offset than your wheels and 315s without issues. with the Pro kit springs you will be fine. i can all but guarantee you will not rub. looks wise, well that is subjective. have you driven the car with the wheels/tires on yet? or are you just worried its going to rub.

Have not driven the car. Agree its not likely to rub, but isn't that due to the bumpstops limiting travel? I show about 50mm fender to wheel clearance, and my bump stops is about 20mm from the frame bracket.

re: the tires - Pretty sure you are right - the Cup 2s run really wide. I am going to try the AUDI version of the same tire in the same 305/30 size, which according to Tire rack runs the SAME section width but 3/4 inch LESS tread.

if you were to use the same tire but drop to a 10.5" wheel, it would be worse. the wider the wheel is, the more stretched the tire is and you get more clearance. with the offset you have, you should not be affected by the bumpstop bracket, even at full droop. i dont think so anyways. your wheels are pretty much fender flush. if you were to push the wheels in more (add more offset) then yes they will hit at full droop. but only when the wheels are hanging in the air. not while driving. the solution? just jack the car up enough to get the wheel on/off. my own car does this lol. i havent relocated the brackets. im running 20x11 on 295 mpss with a few more mm offset then your wheels.

I think you are exactly right.

I measured the tire/wheel in full droop comparing factory 20X9.5 50mm offset to the forged wheel 20X11 55 mm offset. The factory wheel has about 34mm of clearance to the bump stop bracket in full droop. Once I put the 11 inch wheel on it - I only have about 6 mm. By my calculations, I should have 10ish mm (a 55mm offset should move the wheel in 24 mm) BUT the wheel has a big rounded lip on it on the inside bead of the wheel, so I think I lose 3-4 mm or so.

I am guessing I don't really want to get any closer than that? The wheel maker said they would cut another 3mm out, but after measuring, would you advise against it? (I presume the axle moves around in the rear side to side?)

I know I can remove the bump stop bracket but I would rather not.

if the look of how it sits bugs you, call the wheel manufacturer and ask them if they can possibly shave some material off the backpads to bring the wheel in some. we do this all the time and depending how the wheels are cut, we can remove up to 5mm of material. anything less than 3mm is not really worth the effort of sending them back though. 3mm = .118" which should make you happy and not really that much material for them to remove. if theyre willing. that's the key.

See above - Im afraid that my 6mm or so clearance is the limit before I get rubbing on weird inclines or hard side motions of the axle? I drive the car hard sometimes, and I can get heavy bounces in the rear on hard turns.

how your car sits now, OR if you are able to remove a few mm off the backpad, will require no modifications to your car. *if somehow they can remove a whole 5mm off the back, then the tires themselves could possible rub on the inner fender wells during hard cornering, due to them being Mich.. i experienced that when i ran 19x11 with 325s.

Thanks - great data point.

no offense to you at all but i would have to say that i cant blame the company for the offset they used. that's a good offset. you cant expect them to know the widths/profiles of every different tire and every different car. i know because i own a gt500 and have done lots of experimenting. most companies use 51mm which is straight up flush. MOST mustang owners dont run wide tires. most use 275/285 and that offset makes the wheels/tires nice and flush. so they were actually a little conservative. they are probably afraid to go in any more in fear of running into something.

No offense taken - actually my gripe was primarily with the company that sold me the package - the wheel maker wasn't even aware of the brand of tire, just the size. I expected the tire guy to do his homework but apparently didn't - Now its my job to straighten it out. I certainly couldn't do it without folks like you being willing to help. Very grateful...

as i mentioned in my pm, a non-lowered car with a high offset wheel will run into rubbing problems. when you lower the car, it drops the bumpstop bracket below the rim. on a stock car, its right there. we've been putting wheels on gt500s since day 1 and yet we only found this out a few months ago lol. a customer order 20x11 with 315s for his bone stock gt500. they tires actually got stuck on the bracket, at ride height. the easy solution? just a slight drop solves the issue. the reason i mention this experience is to support my statement why companies are careful about putting too much offset on the wheels.

Are you concerned that if the car unloads in a high speed situation it might rub? I'm most concerned that if it did at speed, it would "brake" the wheel and do weird stuff in the rear...

as far as your section width questions, i have no idea lol. as mentioned, there is no industry standard for measuring the width of a tire. i put a 315 nitto NT05 next to an mpss 295/35/20 and they were pretty much the same width. as far as contacting michelin, i wouldnt expect to get anywhere with that. theyre a BIG company. that's like trying to get ahold of a ford engineer to ask a specific question about your car. not to mention michelin is a french company making it even less likely to get ahold of anyone with any real knowledge on the subject.

I have found that out already. The "tech" that answers the phone knows nothing, and my email has gone unanswered.

hope that helps

Immensely. Again - many thanks[/QUOTE]

 

[Dinosgt]

Sorry folks - posting error

 

[Dinosgt]

Thanks to Steve for the great post.

As far as wheels / tires rubbing the bumpstop bracket... Just cut it off. Seriously. I was scared to cut out mine, until I actually did it. It's just some ugly ass piece o metal, takes 15 minutes to cut and paint. I've never don't anything like that before and my wheel wells look like they came like that from the factory

Agree - Steves post was super helpful.

Thanks for the input. I am really trying to keep from cutting off the brackets. If I find that impossible, I will have to reconsider.

Cheers...

 

[Steve@TF]

first of all, i didnt even notice the tire is a 305/30/20 lol. i was thinking 305/35/20. so you have even more wiggle room/fender gap. you will never rub. i had eibach sportlines on my car previously with the bumpstops cut in half, never had any issues. the bumpstops are to prevent the body from bottoming out on the axle. without a bumpstop, it would bang. had that on a slammed truck before that need a c-notch lol. your suspension isnt springy enough where it would be bobbing up and down to the point where you will hit the tires.

if they can shave 3mm, go for it. that's over 1/10th of an inch which helps. that puts you closer to the optimal offset. if you have them do that, you'll be almost to the point where i would have made them for you (for all intents and purposes, youre there). you will not hit bumpstop bracket while driving, ever. you dont need to relocte it either. you are in 100% normal territory even if you move the wheel in 3mm more. the only time contact will be made will be when the wheel is at full droop (on a lift or floor jack all the way up). and that's only an issue when youre trying to remove the wheel. so when you do need to do that, just remember to jack it up just high enough off the ground (like an inch) to remove the wheel.

yes, the axle does move to the side, a little. to the driver's side i believe. but very very little. you wont hit the outer fenders and you'll never hit the bumpstop bracket unless you go off a jump dukes of hazard style. ive experienced the tires rubbing on the inner fenderwells, above the bracket, during hard cornering when i ran 19x11 on 325s. those had a hair more backspacing and were on 325s.. and my car was slammed on sportlines. and all that did was make some rub streaks on the inner fenders. didnt do anything to the tires at all. you shouldnt have that issue with this set up.

keep in mine, there are guys who relocate the bracket and run 20x11.75" and even 12" on 335s lol and say they have no real issues. ive put 11.5" on these cars with the bracket in place, with no issues. so you will be fine.

take the wheel company up on their offer to shave that material off. you'll be pleased with the results.

just my opinion, but you should offer to cover the shipping back and forth. they made them correctly. you just want to make some adjustments per your personal preference, which is fine. but dont ask them to pay for that. theyre doing you a favor here by doing extra machining work which im sure they wont charge you for.

also, a watts link will help control the axle side to side movement. expensive but a nice upgrade to your car's suspension.

*i was typing this up in my reply pm but figured i might as well post it here since you asked here as well. no need to type twice lol

 

[Steve@TF]

Agree - Steves post was super helpful.

Thanks for the input. I am really trying to keep from cutting off the brackets. If I find that impossible, I will have to reconsider.

Cheers...

you wont need to. dont overthink it. even if you decided to go with Toyo R888s in 315/30/20 (run wiide) next time you'll still be ok.

 

[Dinosgt]

first of all, i didnt even notice the tire is a 305/30/20 lol. i was thinking 305/35/20. so you have even more wiggle room/fender gap. you will never rub. i had eibach sportlines on my car previously with the bumpstops cut in half, never had any issues. the bumpstops are to prevent the body from bottoming out on the axle. without a bumpstop, it would bang. had that on a slammed truck before that need a c-notch lol. your suspension isnt springy enough where it would be bobbing up and down to the point where you will hit the tires.

Yes - 305/30. I have about 50 mm gap from the fender to the tire before it contacts (vertically of course). Im thinking with the bumpstop only about 18 - 20 mm to the frame, its probably never going to hit the outer fender. I just don't care for the look of the tire not tucked.

if they can shave 3mm, go for it. that's over 1/10th of an inch which helps. that puts you closer to the optimal offset. if you have them do that, you'll be almost to the point where i would have made them for you (for all intents and purposes, youre there). you will not hit bumpstop bracket while driving, ever. you dont need to relocte it either. you are in 100% normal territory even if you move the wheel in 3mm more. the only time contact will be made will be when the wheel is at full droop (on a lift or floor jack all the way up). and that's only an issue when youre trying to remove the wheel. so when you do need to do that, just remember to jack it up just high enough off the ground (like an inch) to remove the wheel.

Thanks - I noted earlier what concerns me is that I only have 6 mm from the RIM to the FRAME. If it were the tire to frame, I would be more comfortable. these wheels have a large 1/2 round lip on them, which I am guessing is a bit 3mm deep. So I am probably going to let it go for now, and keep trimming them down in my back pocket if a new set of tires doesn't work.

yes, the axle does move to the side, a little. to the driver's side i believe. but very very little. you wont hit the outer fenders and you'll never hit the bumpstop bracket unless you go off a jump dukes of hazard style. ive experienced the tires rubbing on the inner fenderwells, above the bracket, during hard cornering when i ran 19x11 on 325s. those had a hair more backspacing and were on 325s.. and my car was slammed on sportlines. and all that did was make some rub streaks on the inner fenders. didnt do anything to the tires at all. you shouldnt have that issue with this set up.


keep in mine, there are guys who relocate the bracket and run 20x11.75" and even 12" on 335s lol and say they have no real issues. ive put 11.5" on these cars with the bracket in place, with no issues. so you will be fine.

Good to know- What brand tires were the 325s you ran and what was the offset? I'm thinking you are correct that the Michelins run real wide. I have seen many cars with other brands that seem to fit

just my opinion, but you should offer to cover the shipping back and forth. they made them correctly. you just want to make some adjustments per your personal preference, which is fine. but dont ask them to pay for that. theyre doing you a favor here by doing extra machining work which im sure they wont charge you for.

I agree - its not really the wheel makers fault. I was more annoyed with the guy that sold me the "guaranteed to fit" package after I told him all the specs and requirements.

Again - thank you very much for helping me out.

 

[Steve@TF]

on my own car i ran 19x11 with Nitto Invos in 325/30/19. on a customers Boss i did 19x11 on 325/30/19 mpss. both cars had 57mm.

 

[Dinosgt]

on my own car i ran 19x11 with Nitto Invos in 325/30/19. on a customers Boss i did 19x11 on 325/30/19 mpss. both cars had 57mm.

Hmm....Did the Nittos hook? That's the main reason I wanted to try the cup 2s. Didn't want drag radials but hate the Goodyears...

Cheers.

 

[Steve@TF]

Hmm....Did the Nittos hook? That's the main reason I wanted to try the cup 2s. Didn't want drag radials but hate the Goodyears...

Cheers.

my car wasnt pullied at the time lol. im sure they wouldnt. the invo isnt a very sticky tire.

 

[ShelbyGT5HUN]

I'm running a 285/35/20 Invo. Absolutely no traction in 1st and 2nd. Just a pulley and tune here, power-wise.

 

[Dinosgt]

I'm running a 285/35/20 Invo. Absolutely no traction in 1st and 2nd. Just a pulley and tune here, power-wise.

This was my fear. My motor is basically stock (with an exhaust and res delete, so zero added HP), and it blows the goodyears off in 1-2 as well. I'm getting old, and countersteering at 70 may sound cool, but it aint...

Ergo - my desire to try the Cup2s

Update for the thread, I'm have been convinced that the Audi version of the 305/30 in the cup two MAY give me the 3-4mm I need, so I shipped the Porsche set back for a new set.

Will let everyone know how it turns out.

 

[enormous]

I'm on my second set of 325 30 20 Cup 2's and find this tire to be a very comfortable and quiet for a track street tire. They are quieter than the MPSS that I run up front.
Awesome street/performance tire the way I see it.

 

[Dinosgt]

I'm on my second set of 325 30 20 Cup 2's and find this tire to be a very comfortable and quiet for a track street tire. They are quieter than the MPSS that I run up front.
Awesome street/performance tire the way I see it.

Thanks for the feedback - What rims are you running in the rear and at what offset? I presume you cut the bumpstop bracket?

cheers...

 

[V8Flexin]

Didn't think to just go and take pictures of a couple gt3, 4's, & 3rs's here at my job running those cup2's in that size on what I would think are 11” rims.

Sent from my PURE XL using the svtperformance.com mobile app

 

[Dinosgt]

Didn't think to just go and take pictures of a couple gt3, 4's, & 3rs's here at my job running those cup2's in that size on what I would think are 11” rims.View attachment 83453View attachment 83454View attachment 83455View attachment 83457View attachment 83460View attachment 83461View attachment 83462View attachment 83463View attachment 83464

Sent from my PURE XL using the svtperformance.com mobile app

A) Thanks very much for the pics. I am amazed how different the brands look on profile. The cup 2 s bulge quite a bit on an 11 inch rim while these are almost flat in profile.

B) You have a cool Job - Congrats.

 

[V8Flexin]

The first pics are the cup2's @ 305/30/20 and the others are @ 295/30/20. I didn't take any of the RS due to tire size of 325/30/21 was pointless. I actually work on the Mercedes side of the dealership and we don't usually see any track tires mounted. Mostly the MPSS and Conti DW on the amg's which is where I get my good take-off's. I meant to go see what size and brand tires the 918 ran.

Sent from my PURE XL using the svtperformance.com mobile app

 

[Dinosgt]

The first pics are the cup2's @ 305/30/20 and the others are @ 295/30/20. I didn't take any of the RS due to tire size of 325/30/21 was pointless. I actually work on the Mercedes side of the dealership and we don't usually see any track tires mounted. Mostly the MPSS and Conti DW on the amg's which is where I get my good take-off's. I meant to go see what size and brand tires the 918 ran.

Sent from my PURE XL using the svtperformance.com mobile app

Really appreciate the pics. Thx