Metric Tire Sizing

[Skuzzlebutt]

Do you know of any site with a chart or formula to convert a metric size tire to a simple inchxinch-inch size? Perhaps including the antiquated Letter sizes?
Frinstance: a N78-15 = 32.5x9.5-15 = LT(?)

 

[ford67bronco]

http://www.4wheelerssupply.com/Tech/tire_calculator.php

http://www.onlineconversion.com/automotive.htm

hope one of these help.

 

[ASE-73]

I use the BFG Web Site (since I run Mud Terrains) ... their metric tires have inch specs in the SPEC section. They spec actual widths based on rim size, so the data is that much more accurate.

Beware ... conversion calculators make generic assumptions that may not be accurate based on actual tire design and construction.

 

[rstgermaine]

Metric tire sizing is easy. First, remember that one inch = 25.4 centimeters. Now the first number is the tread width in centimeters so divide that by 25.4 to get inches (Ex-255 equals 10 inches). The next number is what's known as the aspect ratio and what that is is the sidewall height as a percentage of the tread width. A 70 aspect ration means that the sidewall is 70% of the treadwidth so in the first example, the sidewall would be 7 inches tall. The last number is the rim diameter in inches (why inches while the rest is metric I'll never know). With a tire size of 255/70R15, the treadwidth should be 10 inches and the overall diameter should be 7+15+7=29 inches.