Wheel Upgrade

[GatorSS/RS]

After 3 years I'm about to upgrade my wheels with MRR M017 I have a 2015 SS/RS with the stock front 8 inch front and 9 inch rear wheels but I'm going with the 10 inch front and 11 inch rear. For tires, I'm going with the BF Goodrich Comp-2 A/S with either 275 or 285 on the front and 305 on the rear. I haven't done anything to the suspension, though I might consider lowering it at a later time. In going through the past posts, it looks like quite a few of you have already done this and I'm wondering if I will notice a significant changes in handling or if there is anything else I should consider? This is my daily driver so I probably won't AutoX but hope to eventually do some of the local drag meets.

[Rock-It Man]

I have the tires you are considering, only in the original sizes. They are great all-season, high performance tires.

Just make sure you go with front and rear tires that are the same diameter, or you will drive the traction control system nuts.

Check out the specs on tirerack.com. I think the 285's are the wrong diameter.

[GatorSS/RS]

The SS/RS uses an 8 inch wheel with 245/45-20 on the front and a 9 inch wheel with275/40-20 on the rear. Since I'm switching over to the ZL1 size wheels though, 10 on the front and 11 on the rear, they list 285/25-20 on front and 305/25-20. I believe they should work but I'm somewhat concerned.

[PROZ11]

Those sizes won't cause and Stabilitrac issue, but If you go from the stock 245/275 sizes to the tire sizes you posted your tires are going to have a 3 inch smaller/shorter diameter. Just mentioning, I'm not sure if you realize that or if that's what you are looking to do. You will have a big gap, not to mention your spedo will read high by about 8 mph at 65 and your rpms are going to go up and your gonna take a hit in mpgs. 285/35 - 305/35 would be a better choice IMO.

[GatorSS/RS]

Yikes, my bad, 285/35-20 and 305/35-20 are the correct sizes according to tire rack. Not sure if my eyes were still waking up or my fingers weren't working typing So, would going with the 285/35 and 305/35 require a change in the computer for proper speedometer operation? Any impact on MPG?

[PROZ11]

Originally Posted by GatorSS/RS

Yikes, my bad, 285/35-20 and 305/35-20 are the correct sizes according to tire rack. Not sure if my eyes were still waking up or my fingers weren't working typing So, would going with the 285/35 and 305/35 require a change in the computer for proper speedometer operation? Any impact on MPG?

No, those sizes would only be about a quarter inch off of the dimater of stock sizes. You be looking at about a half a mile an hour off at 65 mph. Virtually no effect on mpg or mph to worry about. No changes needed.

.

[Rock-It Man]

Originally Posted by PROZ11

No, those sizes would only be about a quarter inch off of the dimater of stock sizes. You be looking at about a half a mile an hour off at 65 mph. Virtually no effect on mpg or mph to worry about. No changes needed.

.

Wrong! The 285/35 is 27.9" and the 305/35 is 28.4". That's .5" difference which is too much.

A better match for the 305 is the 275/40 which is 28.7". That's a .3" difference.

The 245/45 is even closer at 28.6, but it's not going to fit a 10" wide rim.

[PROZ11]

Originally Posted by Rock-It Man

Wrong! The 285/35 is 27.9" and the 305/35 is 28.4". That's .5" difference which is too much.

A better match for the 305 is the 275/40 which is 28.7". That's a .3" difference.

The 245/45 is even closer at 28.6, but it's not going to fit a 10" wide rim.

A half inch isnt too much. Others are running that combo with no issues.

[witenite]

Originally Posted by PROZ11

A half inch isnt too much. Others are running that combo with no issues.

I've had this combo (285/35 and 305/35) since 2015 with zero issues.

[Mike14bumblebee]

Originally Posted by Rock-It Man

Wrong! The 285/35 is 27.9" and the 305/35 is 28.4". That's .5" difference which is too much.

A better match for the 305 is the 275/40 which is 28.7". That's a .3" difference.

The 245/45 is even closer at 28.6, but it's not going to fit a 10" wide rim.

I'm pretty sure you are the wrong one here. Zl1 sizes have no issues. Anything over 1" difference in diameter will throw off stabilitrac. I have 285-35 on my fronts and just put 315/35 Nittos on the rears with no issues.
To OP, only difference you may notice is the car will pull more as the wider fronts like to follow the grooves in the road.

[Rock-It Man]

Originally Posted by Mike14bumblebee

I'm pretty sure you are the wrong one here. Zl1 sizes have no issues. Anything over 1" difference in diameter will throw off stabilitrac. I have 285-35 on my fronts and just put 315/35 Nittos on the rears with no issues.
To OP, only difference you may notice is the car will pull more as the wider fronts like to follow the grooves in the road.

I would look at the specific manufacturer's specs before buying a non-standard combination of front and rear tires.

I don't know what the limit is on difference in diameter, but obviously, the traction control system is looking for changes in rotation rates between corners, so if there's a difference from diameter alone, the system is going to take action sooner than if the tires are all the same size.

[GatorSS/RS]

I appreciate all the responses. Thank you very much

[Mike14bumblebee]

I'm just saying the zl1 comes factory with 285 and 305 obviously with no issues. And many others on here have swapped rears for 315s, as did I, with no issues.