Saw this and thought of you - Tyre strech calculator

[AxlFoley]

I'm not sure how scientific it is although it seems to be quite good, Its will be good when choosing different wheels and offsets, you can comare it with what you have at the moment to see how much the tyre and wheel will move

http://www.tyrestretch.com/files/Tyre%20Calculator_English.xls" onclick="window.open(this.href);return false;