Calculate Tire Diameter
How do you calculate Tire Diameter
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So how do you calculate the diameter of your tire based on the letters and numbers printed on it?

Basically all tires have something like this printed on it:

And if we label all the number above like this:
Type Width / Ratio Radial Rim

Then the tire diameter formula is as follows:
(((Width x (Ratio/100)) x 2)/ 25.4) + Rim = Tire Diameter

However, if you don't have a calculator handy, you can simply fill in the information here and we will calculate the tire diameter for you:

Tire Diameter Calculator
/ R =

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Here is a more detailed explanation of the different parts printed on the tire:

Type: Tells you what kind of tire it is:

P = Passenger vehicles tire (most cars and trucks)
T = Temporary tire (smaller tire)
LT = Light Truck tire (larger SUVs, pickups etc)
ST = Special Trailer (boat trailer etc.)

Width: This number tells you the width in millimeter of the inner walls of the tire. (you can devide millimeter by 25.4 to get inches)

Ratio: This number tells you the distance from rim to tread as a percentage of the width above.

R = Radial (you can sometimes also find D for Diagonal and B for belted)

Rim: The last number indicates the inner diameter and should match the wheel and range from 9 to 28.

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