Ive got 18x9's on ther rear with 18/265/35 tyres on..
Had to have the guard rolled.. but it fits perfectly now and doesnt scrub
Front are 18x8 with 18/245/40 and just miss.. ever so slight scrub at full lock going into a driveway etc
sitting on Tein coilovers
Rim offset will also come into play..
If i was buying again id get 18x8's on the rear... but my rims were 2nd hand and too much of a bargain to pass up