Posted by Jim Turner on May 01, 1999 at 10:51:30:
In Reply to: TIRE SIZE CALCULATIONS....HELP!!! posted by Will on April 29, 1999 at 23:34:11:
I too have been looking at some new tires for my '95 Astro van. I have found thie little
bit of math to be of some help to fine out just what the tire dia.is in inches. It goes
like this :: tire dia = (2 x section width) x (aspect ratio) / (2540) + (wheel dia)
for my P215/75R15 tires it was :: 2 x 215 x 75 / 2540 + 15 = 27.7 ( ok it's 27.6985039)
Now that I have this all I need do is check the tire dia. of any tire that I may want
to use on my van. The trick is to try to get as close to your OEM tire dia. as you can.
If you go to a wider tire you will most likely have to go to a smaller aspect ratio also.
Hope you find this to be of some help to you.
JT