Jul 14 2010

How do you read tire sizes? What do the numbers and letters mean?

Category: Automotive


Here is an example of how to read one of the most popular tire sizes – P225/60R16.

1st Letter = Vehicle Type
The first identifier is the letter in front. It represents the type of vehicle that the tire was designed for. It can be a P, T, LT, C, ST or have no letter at all.

P – Represents a passenger vehicle. Passenger vehicles will include cars, minivans, SUVs, and small pickup trucks. Generally the most used and popular tires.

T – Represents a tire made for temporary use.

LT – Represents a light truck metric and was made for use on vehicles that include medium and heavy duty trucks.

C – Represents a commercial tires used on trucks that have the ability to carrying heavy loads.

ST – Represents a special trailer tire. Are designed for towing other vehicles. Should not be used on vehicles.

1st Number = Section Width in mm
After the letter indicating vehicle type, a number will follow. This number is typically the width of the tires in millimeters. How fat are the tires? is indicated with this number.

2nd Number = Aspect Ratio (Profile)
The next number in the series is the profile of the tires or the distance between the rim and tread. It is calculated a bit differently. The number indicates a percentage of the size of the section width. So in this example it would be 60% of 255 or 135 millimeters or 5.314 inches.

2nd Letter = Internal Construction
The next letter will identify the tire’s internal construction. It will follow the two digits used for the aspect ratio. In most cases, the letter will be an R, identifying that this is a radial tire. Radial tires represent 98% of the world tire market and are the most popular tire sold.

3rd Number = Tire and Wheel Diameter
The next number will indicate the tire and wheel sizes. These numbers represent inches and the corresponding wheels or rims are typically sold from 16in to 36in (sometimes more).

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