Tire Size Help

[Jeronimo]

Did some research and saw others running bigger tire sizes with no issues so I pulled the trigger on a new set up but I’m having some rubbing issues. Not sure where I went wrong.

I’m running 20x9 front with 285/35r20 and 20x11 rear with 305/35r20. I have a comp so I’m not sure if maybe the suspension is lower causing the rubbing but on my last M6 non comp I ran this and had no issues. Rubbing while turning I don’t mine but the rear rubs when going over simple bumps.

Any help is appreciated. Might be a dumb mistake on my part but can’t figure it out.

[byebyev8]

Your tires are too tall

[M6-Coupe]

There are several issues with your car.
1. The front tire is increased significantly ( about 0.6" taller)from 265 to 285
2. Your rim is 9" good for 265 but for 285 you need atlas 9.5"
3. your rear tire is increased significantly (about 1.4" taller) from295/30/20 to 305/35/20
You probably get lots of vibration and are loosing the dynamic of car.

[Aliendex]

Your rims are not OEM, so you have to take into account also the new ET to calculate exactly where your wheels will sit inside the fender.

Also, I would personally keep 305/30 R20 in the back, no need to increase tire sidewall at all.

295/30 sidewall: 88,5mm
305/30 sidewall: 91,5mm
305/35 sidewall: 106,75mm

From OEM to your setup, you have increased your sidewall by 18,75mm, this means your tires are 18,75mm closer to the fender.
You are also 18,75mm higher from the ground (good for ground clearance)

And if you multiply by 2: 18,75*2 = your tires are 37,5mm larger than OEM, which is A LOT for the traction control and also for the driveability of the car.