Quote Originally Posted by Stargazer View Post
Sorry, I'm a bit of a noob with tyres. I used the calc on http://www.carbibles.com/tyre_bible_pg2.html

It calculates the circumference of my 205/55/16 to be 1985.17mm and the circumference of the 225/40/18 to be 2001.82mm, a diff of 16.65mm.

The 245/35/18 only gave a 10mm difference (decrease) in circumference. I did notice this tyre size seems to be less popular - some manufacturers don't seem to even make this size. But I do like the thought of having wider tyres too. My mind is boggling at all these numbers and choices! Will the 245/35/18 fit a 18x7.5 wheel?
You would be pushing it, you really need an 8 inch wheel for a 245. Max on a 7.5 inch would be a 225.

Try this calculator I found it useful when I was looking for wheels.

http://wheelsmaster.com/rt_specs.jsp