Ever get into the trouble finding the right size and height profile when your original tyre has the odd height profile eg. 65% ? Then this is a very useful tyre calculator which guides us to correct substitute particularly when we start changing the wheel diameter as well which then complicates further making the right call. This is important to ensure ride height and gearing is maintained. I guess this explains why I keep scrapping some speed hump despite going slow over it sometime.
http://www.tyresave.co.uk/tyresiz2.html
