[Jeza]

Tyre size will come into it, but most important is the wheel width and offset (or backspace). If you want to run wide wheels you may find they interfer with the springs. The way around this is to use the slim spring struts- which are more expensive.

Have a look around here and on the Topline site, then have a talk to Big Boys Toys and the like (Machine 7) they should be able to point you in the right direction.

Cheers
Jeremy