[JamesNoBrakes]

I run 295 michelins and Falkans up front on the stock wheels, no issues. It does give you more sidewall flex, which isn't the best thing for hard cornering, but they are such good tires it doesn't really give up anything IMO.

For both, I couldn't really get the size I wanted, the michelins in 285 were all scooped up by OEM cars and there was a major supply issue. With the autoX tires, there really weren't a great amount of sizes to choose from, so 295 square was the best idea at the time.

[Msquared]

If 285/30/20 isn't available in the tire you want, then 295/30 will be fine.

Those who are recommending 275/35/20, do you understand that those are 0.4" taller than the 305/30/20 rear tires? You don't want that for a number of reasons.

[Justcruising]

Originally Posted by SSShark

Thanks Justcruising. I was hoping that someone with that setup would weigh in. Are you running the 305's in the rear?

No Im running 315/30/20 on the rears

[2SS Capt]

Originally Posted by Msquared

If 285/30/20 isn't available in the tire you want, then 295/30 will be fine.

Those who are recommending 275/35/20, do you understand that those are 0.4" taller than the 305/30/20 rear tires? You don't want that for a number of reasons.

That's why if you run 275/35/20 on the fronts you should run 315/30/20's on the rear (non-1LE SS)... That math, math's out just fine...

245/40/20 --> 275/35/20 (98.0 vs. 96.25)
275/35/20 --> 315/30/20 (96.25 vs. 94.50)

1.82% F-R difference stock
1.85% F-R difference alternate sizing

About as close as you can get...

[Msquared]

Originally Posted by 2SS Capt

That's why if you run 275/35/20 on the fronts you should run 315/30/20's on the rear (non-1LE SS)... That math, math's out just fine...

245/40/20 --> 275/35/20 (98.0 vs. 96.25)
275/35/20 --> 315/30/20 (96.25 vs. 94.50)

1.82% F-R difference stock
1.85% R-F difference alternate sizing

About as close as you can get...

I fixed your statement for you. You arranged your math backwards: the stock SS or SS 1LE has a shorter front tire than rear. Your proposed replacement has taller front tire than rear. It's nowhere near "as close as you can get" regarding tire heights: it's a about a 3.6% swing in the opposite direction! And to add insult to injury, you've now decreased front section width 10mm and increased rear width 10mm. Why would anyone do this intentionally to their car?

What I know from direct experience is that having a 2.6% taller front tire than rear will make the ABS computer unhappy. You can get a flashing traction control light, the car may not allow you to use cruise control, and the ABS will more easily invoke ice mode. Will a 1.85% taller front do the same? I don't know, but I know there's no good reason to try it.

[arpad_m]

Originally Posted by Msquared

I fixed your statement for you. You arranged your math backwards: the stock SS or SS 1LE has a shorter front tire than rear. Your proposed replacement has taller front tire than rear. It's nowhere near "as close as you can get" regarding tire heights: it's a about a 3.6% swing in the opposite direction! And to add insult to injury, you've now decreased front section width 10mm and increased rear width 10mm. Why would anyone do this intentionally to their car?

What I know from direct experience is that having a 2.6% taller front tire than rear will make the ABS computer unhappy. You can get a flashing traction control light, the car may not allow you to use cruise control, and the ABS will more easily invoke ice mode. Will a 1.85% taller front do the same? I don't know, but I know there's no good reason to try it.

Matt, I think you're wrong on this one. The difference from stock SS to these tire sizes is -0.4% (-0.2") front and -0.7% (-0.1") rear, the change doesn't flip the car's rake, the SS has taller front tires even stock. Yeah, this change increases that negative rake a tiny bit (by 0.1" or 2.5mm), but that is negligible.

I'm running this very setup with OEM 1LE wheels, and both ABS and traction control work fine, the speedo is only about half an mph off at 60. Car drives perfectly fine, there is more sidewall than on a 1LE tire setup, which is good for normal street driving, and cornering stability is still excellent.

[SSShark]

Guys, I still stand by my argument that when running the 1LE wheels, the 295 fronts paired with the 305 rears, will give you the most even stance. Making the fronts just .2" lower than the rears.
The 275 fronts paired with the 315 rears makes the front tires .2" taller than the rears. I'd prefer the rear tire to be a tad taller, not the other way around. Just my personal preference.

[WhiteMale]

i never said to run a 275 with a 305 or 315 rear, I only intended to say that it fits the OE wheel. I didn't mean it to be taken that way.

[SSShark]

Originally Posted by WhiteMale

i never said to run a 275 with a 305 or 315 rear, I only intended to say that it fits the OE wheel. I didn't mean it to be taken that way.

No worries whitemale, I knew exactly what you meant.

[2SS Capt]

Originally Posted by Msquared

I fixed your statement for you. You arranged your math backwards: the stock SS or SS 1LE has a shorter front tire than rear. Your proposed replacement has taller front tire than rear. It's nowhere near "as close as you can get" regarding tire heights: it's a about a 3.6% swing in the opposite direction! And to add insult to injury, you've now decreased front section width 10mm and increased rear width 10mm. Why would anyone do this intentionally to their car?

What I know from direct experience is that having a 2.6% taller front tire than rear will make the ABS computer unhappy. You can get a flashing traction control light, the car may not allow you to use cruise control, and the ABS will more easily invoke ice mode. Will a 1.85% taller front do the same? I don't know, but I know there's no good reason to try it.

I am talking from stock SS (non-1LE) sizing to the alternate sizing, my math is correct, both are slightly shorter sidewall than the stock SS (NON-1LE) and the traction control will be fine as the ratio stays very close to the stock ratio...

[DriftR]

Can the GM 1LE wheels fit these... seems perfect?

[SSShark]

Originally Posted by DriftR

Can the GM 1LE wheels fit these... seems perfect?

That 325 is massive, almost an inch wider than the stock 1LE 305's. I'm thinking that's going to rub.

[Msquared]

You guys are right: I completely forgot that stock non-1LE SS cars have slightly taller front tires. So yeah, for that car a slightly taller fitment would probably be fine. And since that's the kind of car the OP has, then this applies to him. I think the 1LE version has differently calibrated ABS and traction control, and I would not say it's a wise fitment for that car. But that doesn't apply to the OP's case.

Sorry for my mistake!

[SSShark]

Originally Posted by Msquared

You guys are right: I completely forgot that stock non-1LE SS cars have slightly taller front tires. So yeah, for that car a slightly taller fitment would probably be fine. And since that's the kind of car the OP has, then this applies to him. I think the 1LE version has differently calibrated ABS and traction control, and I would not say it's a wise fitment for that car. But that doesn't apply to the OP's case.

Sorry for my mistake!

Hey Msquared, no biggie. You're good.
Thought I'd share a pic of my current setup. 285/30 on the fronts and 305/30 on the rears. Car is lowered with the GM Suspension Lowering kit.