Re: [Chrysler300] Tire Math

[dan300f@xxxx]

Hi all:

The formula for calculating the diameter of a radial tire is as follows:

For example, a 235/75R15 
Where: 235 equals the tire width in millimeters
75 is the height of the sidewall as a percentage of tire width
15 is the diameter of the rim in inches

First, converting tire width to inches:

235 mm divided by 25.4 mm/in. = 9.25 in.

Then multiply 9.25 in. by .75 (the 75 in the tire size) = 6.94 in.
(This is the sidewall height)

Then multiply this number by 2 (the tire sidewall height times 2)
= 13.88 in.

Add in the diameter of the rim, 15 in. + 13.88 = 28.88 in.
(the diameter of the tire.)

Have fun.

Dan Reitz
Northridge, CA


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