According to BFG, the widest tyre for a Wolf rim (6.5") was the 235/85.
If memory serves you'll need a 7.5" rim for the 255s.
When I was wondering about fitting the 255s to mine I would have gone for the original Modulars - cheap and relatively robust (with that bit more offset than the standard wheel too).
In the end though I decided that most of my friends were too short to get into the car with them tyres on, so I'll be sticking to the 235/85 for the time being. :lol: