I was bored the other night so I went to Michelin's website. They actually have the chart to convert the sizes on there. They do the tire size the same way (width X aspect ratio X rim size) so the only difference I could see would be if they measure to the widest lug while others use the sidewall to measure? I know its trivial info but i'm still interested in why.
[This message has been edited by Big94Ford (edited 04-08-2001).]