I have looked at a few website that calculate different tire sizes and compares them and some things don't make sense to me. In lets say a 195/60r14 tire I thought the 195 was the width of the tire, the 60 was the thickness of the sidewall, and the 14 is the rim size it's meant for. But after looking at these calulators it doesn't seem to work like that. When I change the width of a tire it effects the overall diameter of the tire. I would think a 195 in a 60 series tire would be the same over all diamter as a 185 in a 60 series tire. But it's not, so why? How does a wider tire in the same sidewall size make the overall tire size bigger? Sorry if this is a dumb question but I've always had stock wheels and never really thought about this stuff before. I tried searching but couldn't really find anything.

 

60 is not the actual height (thickness) of the sidewall. It's called the aspect ratio, and it represents the ratio between the width of the tread and the height of the sidewall. For example, the height of the sidewall on a 195/60-14 tire is 195 mm * .60 = 117 mm. That's why the height of the widewall increases when you increase the width of the tread, leaving the aspect ratio the same.

 

Correct again Mr. H-T Order of Merit :D