Actually, the front tire will be fine on an 8.5" wheel. The rear tire will cover the wheels nice but if you likely plan on lowering your car, you will need to stretch like mexxilis said. Likely a 255/35 with that aggressive offset. Maybe 265/35 if you roll your rear fenders a bit will be a nice fit for the 10" wheel! Or roll them enough to clear your 275/30 so you don't go spending more $$ on tires!
It can be done for sure though
