GP06Roadster
Senior member
Don't know if this has been posted before but may help someone, really excellent online calculator which works out what effect different tyre width and profiles, rim widths, offsets etc have, even works out arch gaps
http://www.willtheyfit.com/index.php?width=255&aspect=30&diameter=19&wheelwidth=10&offset=38&width2=245&aspect2=40&diameter2=18&wheelwidth2=9&offset2=26#content
http://www.willtheyfit.com/index.php?width=255&aspect=30&diameter=19&wheelwidth=10&offset=38&width2=245&aspect2=40&diameter2=18&wheelwidth2=9&offset2=26#content