A few months ago I saw a tire calculator in Truckin'. Maybe I'm dence, but I can't seem to figure it out. If some one could explain it better I would apprieciate it

Right now I have stock 235/70-16's soon I'm going up to a 17" wheel, but want to keep my tire diameter about the same.

 

Troy67,
Try this one found it from someone here.
http://www.dakota-truck.net/TIRECALC/tirecalc.html
Just enter in your size then the size you are looking at and tell it to compare tire A to tire B. The table will show height width overall diameter and speedo error.
Jim

 

Jim A, Thank you. My new tire size will be 275/55-17, about 1.5" wider and 1/2" shorter. Very cool.

 

Multiply your wheel width by the series value. Divide this number by 25.5. Multiply it by two. Add the wheel diameter.

This method will get you to within a thenth of an inch of the actual diamater.

275/50/20 tires

275 x 50 = 137.5 (gives you sidewall height in mm)

137.5 / 25.5 = 5.39 (gives you sidewall height in inches)

5.39 x 2 = 10.78 (gives you overall sidewall)

10.78 + 20 = 30.78 (entire diameter of wheel and tire)

 

THANKS FOR ALL THE HELP, GUYS

 

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

Try that, it'll evn tell you how much your speedo will be off if you change sizes

 

THANK YOU 2FORDS