: Tires and Speed Limits

09-30-08, 05:10 PM
A friend has a 2008 CTS AWD DI with dealer installed aftermarket wheels and 235/50ZR18 l0lW M&S Toyo Proxes 4 tires rated 300 A A. She is worried about tire life and I am curious about where Cadillac set the speed control computer. Iím sure the CTS canít reach the 168 MPH limit on the tires but it could certainly exceed the 112 MPH rating on the Michelin S rated tires on my 2008 AWD STS DI (500 A B) if the computer would let it. Anyone have any brilliant (or even dumb) insight into tire wear and the speed limits on both cars?

09-30-08, 10:07 PM
From my experience, tires rated at 300 will be gone by 15,000 miles. There is an upside though that people overlook... those tires will probably have tremendous grip as they are softer, so doesn't mean they are inferior tires just because they wear out soon. Not sure about speed limiters on CTS, should post in that forum as well.