You can use the size chart comparison in thread #5 to determine the tire's overall diameter. I'm pretty sure a tire can vary about an inch in differential without affecting the car too much. Don't even talk to me about emergency handling situations, because the tire is a different sized and foot print on asphalt. If you take it easy and keep speeds below 50mph, you should be OK. FWIW: traction control tolerances are much tighter on AWD cars, so that the ECU can send power to the wheel with traction.
