Hello all, i apologize if my question has already been asked. I recently discovered a slash on the inside of the tire on my wife's 2015 q3 quattro prestige plus. We bought the car used with 20 in rims running dunlop sp sport signature 245 35 r20 that have since been discontinued. The remaining tires have approximately 8/32 tread left and i am wondering if it's ok to replace just the back two tires with a different brand of tire(continental dws 06 245 35 r20)? Or because of the awd do all 4 need to be replaced?