Re: Tire sizes?

From: Steven T. Ekstrand (cyberlaw@earthlink.net)
Date: Thu Jul 20 2000 - 13:00:46 EDT


| P - passenger car rated
| 255 - tire width (in millimeters, I think)
| 65 - aspect ratio of the tire. The height of the sidewall is 65% the
| width of the tire
| R - Radial
|

Divide the 255 by 25.4 to convert to inches! That is the section width of
the tire, the actual tread width is narrower by a bit.

[(255/25.4)x(.65x2)]+15 gives you the diameter of the tire in inches

That is--- Section width divided by 25.4 times aspect ratio times two and
then add the rim diameter.

Note-there are some manufacturer variations in the actual physical
measurements of the tire. So one 275-60-15 tire may fit and another may
rub if you are very very close to having interference problems. The reason
is one makers tire is a 1/4 wider section width even though the size is the
same. Actual tread width can vary by as much as a 1/2 inch in the larger
sizes between manufacturers.

-STE



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