i need a calculator to calculate the difference in speed between different tyre sizes on a car (just woken up so bear with me )
ok cheers

Try this


[url="http://www.canadiandriver.com/tools/tirecalc/tirecalc.htm"]http://www.canadiandriver.com/tools/tireca...lc/tirecalc.htm[/url]

Remember how much difference tread depth makes.
If you wheel is 30" overall diameter with 8mm of tread, then when the tyres are down to 2mm its only 29.5", thats a 2mph difference at the top end.

Tyre pressure can effect it even more than that, its easy for a wheels radius to be out by 5% cause of different tyre pressures (although less true on low profile tyres)


Chip