Anyone using 285/35R18 on the rear wheels?

[FlashingBlade]

• I was wondering whether anyone is using 225/40R18 on the fronts with 285/35R18 (stock is 30) on the rears on a 2002 996 C2?
• Will this negatively impact the ABS & PSM?

Details:

I have a 2002 996 C2 with 18" rims. Stock rear sizes are 285/30R18 except only 285/35R18 are available for the Michelin Pilot Super Sports.

I have done the math, they are about 1/2" taller in radius, and 81.223 vs 77.698" in circumference 3 -4 % error on the odometer, but my odometer is 10% fast anyway, so I dont care.

I have looked at the forums and have not found a definitive answer.

The tire place does not want to mount them on the car. They called Porsche, and they advised against it. OTOH, Porsche also advises against non N rated tires...Local tuner says it's fine.

Please advise.

[JohnnyDangerous]

285/35/18 gives a tyre diameter of 25.9 and a 245/40/18 a diameter of 25.7 so yes it will be fine, a 255/45/18 is even closer at 26. i run a 315/30/18 and 235/40/18 front.

[Cloudsurfer]

They'll be a hair taller, which shouldn't cause any fitment issues, but unless you correspondingly go up in the front as well, I might worry about the speed sensor inputs being different and pissing off the ABS/ PSM.

It goes without saying that you'll also incur some speedo error.