but if you change front and rear tires differently and have different grip levels on them it messes with your handling.

yeah, but i kind of like that. the fronts ALWAYS have more grip do to the way i have it set up so they wear like this...

New Tires, put old fronts in rear
grip levels way to high to use on street, fun driving, ultimate grip.
rear starting to wear some, tail will come out if you really push it, very fun powerslides.
rear loses it all the time, drifting, fun.
rear down to threads, buy new tires again