Stick a car ramp under opposite corners, that should give you an idea if they're ok
Depends on what suspension setup you're running: length of shock travel, bump stops, etc as to wheter or not they'll rub.
A car ramp will give you an idea of 'flex' at the rear end, but it's likely it'll go beyond that amount of articulation when used in anger!
Great choise of tyre btw.
I used to run 255/85x16 (33's) on my old 90 - found the slightly narrower width worked better on a lighter motor.
