Hi guys I'm ready for some rear tyres on the wagon as they are starting to perish between the tread blocks. My question is with the car being AWD is it ok just to put new tyres on the rear or do I have to change all 4 at once. Just thinking that if I put new rears on they would get scubbed down to the same diameter as the fronts which have about 4.5mm left on them for some reason with it being AWD. Could some one clarify cheers, Steve.