Quote:
Originally Posted by Pavel
I agree that the fact that traction control kicks in can have something to do with different sizes of front and back tires
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I don't know how precisely our traction controls are set, and it's different from car to car. But the way the system works is to detect and respond to a difference in the rotational speed of one or more wheels, because a tire that's not fully engaged with the road (i.e. skidding, slipping etc) will be turning at a different rate from one that's fully engaged with the road surface. A driven wheel with an open diff will be spinning faster if it loses traction. A non-driven wheel (fronts, in our case) or a driven wheel with a locked diff will be turning slower if it's sliding than if it's gripping the road.
Different rolling radius tires turn at different RPMs at the same road speed. This confuses electronic traction and stability controls, which are programmed for a specific ratio of front to rear tire diameter. If the difference in rolling radius between the front and rear tires is great enough (or different enough from the one programmed in to function properly with different F & R tire sizes) to trigger the electronic sensors, the result can be rapid cycling of tiny amounts of "correction" because the computer thinks that one or more wheels is spinning too fast and the car "must" be skidding.
This could be the cause of your handling woes, although Tire Rack is pretty knowledgeable and very careful about advising customers against problematic changes in tire size from OEM.