Originally Posted by Guard Dad

New tires are essentially green and do not develop maximum grip until they have been through several heat cycles. Having new, green tires on the rear can create an oversteer condition. Be aware that mixing different brands/models/sizes of tires can create significant changes in the behavior of your car that may not resolve themselves with heat cycling. Also note that identical tires can preform differently depending on the tread depth. The tires with the shallower tread typically deliver quicker response and greater traction. On a low to medium performance vehicle these differences may not be especially significant but on a car with the quick responses of the 370Z it has the potential to be significant.