'19 GT staggered height/width setup

[Cascadian]

After talking to reps from both LMR and AM, they both advised to install 305/35r20 on 20x10" rears with either 255/40r19 on 19x8.5" front wheels or 275/35r19 on 10" front wheels. Here is a link to a video AM sent me and some screen shots of their recommendations. One forum member messaged me and let me know that most people here are very performance based, while most people that buy parts from AM or LMR are doing so mostly for looks. I can understand that... and I am definitely doing it for the looks. I just don't want it to be dangerous to drive.

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[m3incorp]

I agree there is nothing wrong with hearing what others have to say. Hopefully, you can find something that fits your needs.

I appreciate all the opinions and discussion... and to address m3incorp. No, I am not trying to make the car "drive bad or dangerous". The internet is full of Safety Sallies though, so I was looking for someone with first hand experience about how much the performance degrades for day to day commuting. As I mentioned, this car does not get tracked or driven aggressively on mountain roads. The wheel and tire upgrade is definitely for form over function. I understand most people disagree with that, and in many instances I would too. Just not trying to spend an extra $500+ for performance that will never be needed for a commuter. I was hoping, as a newcomer, to join this forum and be able to pick the brains of people with first hand experience. Nothing wrong with wanting to hear a couple accounts before I am convinced, right?

That being said, thank you NightmareMoon and Norm Peterson for the info. I will have to maybe rethink my tire and wheel choice to find something with better matched sizes. By the way, you mentioned 10/11" wheels are easy to find. Would you mind pointing me in the right direction? Only ones I have been able to find with correct offset was on AM or LMR. I was talking to someone at N4S / Project-6GR, but they never got back to me. I probably wouldn't trust them anyways after hearing what you guys are telling me because he was recommending a 325 rear tire on an 11" wheel and 285 fronts on 10s. Both oversized again. He sent me several customer cars and they all looked great, but I suppose going with something like that would drive bad or dangerous?

 

[Cascadian]

Is there any potential problem with having rear tires 1.15" taller than factory and 1.4" taller than the front tires?

 

[MidwayJ]

After talking to reps from both LMR and AM, they both advised to install 305/35r20 on 20x10" rears with either 255/40r19 on 19x8.5" front wheels or 275/35r19 on 10" front wheels.

I'm surprised LMR didn't recommend 20x11 rears to go with 19x10 fronts. Why "stagger" the tire width but not the wheel width?

The big difference in diameter between rear and front will give you a raked look and fill wheel gap in back but not in front.

 

[NightmareMoon]

Thanks for the info. I had a look and it doesn’t look like MRR or Apex carry any wheels in 20” diameter. I’d really like to stick with 20” rears. The SVE S350 wheels don’t come any wider than 20x10” but they sell all their staggered wheel setups with 305s in the rear. Is running a 305 on 10” rear wheels acceptable? I’m wondering if the tire roll issue would still be a problem if I had 275s up front on 10” wheels?

285 fits a 10” well, 275 is fine too. Stretching the tire a little like a 275 on a 10” or 295 on an 11 isn’t a bad thing at all.

 

[Rick#7]

The factory setup on my car was 255/40 on an 8.5" rim. The factory has a pretty high safety margin they must keep to, so I really doubt going to a 275/40 tire is going to suddenly make the car dangerous. It just isn't ideal in terms of getting the best performance out of the tire. If the rim you like only comes in a 8.5" width, and you want the 275/40 for looks, I think it's doable for strictly commuter driving, but I know that opinion is in the minority here. I'm currently running 255/35 on a 20x9 in front, and honestly the tire looks too small to me. Remember the wheel lip is 1/2" thick, so my 9" rim is really 10" wide, and those 255's leave just a tiny bit of wheel lip poking out. It's great for tread stability in hard cornering, but not so great when you get too close to a curb. I prefer a more filled out look so when I get a bit more tread wear on these I'm definitely going to a 265 or 275 tire.

If you're going to stagger tire height by nearly 1 1/2" with the stock ride height, the smaller fender gap in the rear will make the car look like it's squatting. The factory stance already has a little more fender gap in front than the rear, the staggered sizes you mentioned will just exaggerate that look, but if you install lowering springs on just the front to equalize the fender gap, it will look much better and have an aggressive raked stance.

The other thing I'm wondering about is at some point when staggering tire diameters the difference in wheel speed will fall outside the limits of the traction control system and it may think the car is in a spin or a lost traction situation, I just don't know if 1.5" difference is at that point or not.

 

[shogun32]

There is no danger to drive. Tc cares about sudden and large changes in relative wheel speed. Not steady state.

 

[Norm Peterson]

The factory setup on my car was 255/40 on an 8.5" rim. The factory has a pretty high safety margin they must keep to, so I really doubt going to a 275/40 tire is going to suddenly make the car dangerous. It just isn't ideal in terms of getting the best performance out of the tire. If the rim you like only comes in a 8.5" width, and you want the 275/40 for looks, I think it's doable for strictly commuter driving, but I know that opinion is in the minority here. I'm currently running 255/35 on a 20x9 in front, and honestly the tire looks too small to me. Remember the wheel lip is 1/2" thick, so my 9" rim is really 10" wide, and those 255's leave just a tiny bit of wheel lip poking out. It's great for tread stability in hard cornering, but not so great when you get too close to a curb. I prefer a more filled out look so when I get a bit more tread wear on these I'm definitely going to a 265 or 275 tire.

If you're going to stagger tire height by nearly 1 1/2" with the stock ride height, the smaller fender gap in the rear will make the car look like it's squatting. The factory stance already has a little more fender gap in front than the rear, the staggered sizes you mentioned will just exaggerate that look, but if you install lowering springs on just the front to equalize the fender gap, it will look much better and have an aggressive raked stance.

The other thing I'm wondering about is at some point when staggering tire diameters the difference in wheel speed will fall outside the limits of the traction control system and it may think the car is in a spin or a lost traction situation, I just don't know if 1.5" difference is at that point or not.

Couple things here . . . tires with lower profiles than 50 aren't even supposed to look the way 60 and 70 series tires used to look (significant amount of sidewall showing out past the wheel) . . . and the portion of the wheel that you called a 'lip' is really called a flange. Wheel flanges actually come in more than one contour (it's those J or JJ or JK letters that you sometimes see in wheel spec lists).


Norm

 

[Rick#7]

Thanks for the info. Yeah, my taste definitely leans towards the old school 50 and 60 profiles, and I know 20" rims on the S550 will never have that look, but honestly I mostly just want a little extra margin against curb rash. As it is right now with 255's up front, the flange literally pokes out beyond the sidewall by a small bit, so if I get too close to a curb the flange is what hits the curb 1st and by the time I feel it hit, it's already left a mark. In spite of how careful I try to be, in the year since I put these 20's on my car I've had 3 incidents of trying to maneuver in very tight situations that resulted in kissing a curb. I fully believe if I had just a little more tire on the rims, the tire would've touched the curb 1st and I could've stopped before scraping the flange, or at the very least had much less noticeable rash from it.

If there were a better selection of 18" or 19" rims that clear GT brakes, and tire sizes to fit them in the width I wanted for the rear, I probably would've gone that route, but the rims I wanted don't come in 19", and the 18" won't clear GT brakes, so I went with 20" which means 35 or 30 profile sidewalls, and widths that don't protrude much beyond the flange of the rim. I still believe the flange doesn't have to stick out past the tire though, and for my preference, a tire that's just a little wider than the rim (including the flange thickness) is beneficial, for both preventing curb rash and for looks.

 

[Norm Peterson]

If there were a better selection of 18" or 19" rims that clear GT brakes, and tire sizes to fit them in the width I wanted for the rear, I probably would've gone that route, but the rims I wanted don't come in 19", and the 18" won't clear GT brakes, so I went with 20" which means 35 or 30 profile sidewalls, and widths that don't protrude much beyond the flange of the rim. I still believe the flange doesn't have to stick out past the tire though, and for my preference, a tire that's just a little wider than the rim (including the flange thickness) is beneficial, for both preventing curb rash and for looks.

I understand the situation where choices are limited by product availability completely.


Norm

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