tire sizing

How do you size tires? You know, so you raise the diameter of the tire by an inch or two, but how do you know how much the width and height changes as you change the diameter?

Try this: http://www.miata.net/garage/tirecalc.html

That's a good tool for calculating sizes.

The way tire sizes work is really dumb, if you ask me.

The first number is the width in milimeters.
The second number is the height of the sidewall, as a percentage of the width.
The third is, of course, the rim size.

How do you size tires? You know, so you raise the diameter of the tire by an inch or two, but how do you know how much the width and height changes as you change the diameter?

the most important thing is load capacity......if you change sizes the next is clearance....don't want to blowout tire when going down the hwy if it scrapes wheel wells....when you hit a dip in road...finally compare revs/mile with oem and what you think you want to use....

The third is, of course, the rim size.

Which is in inches.

So we get metric, a percentage and imperial all in the same sizing.