How Tire Dealers Name Tires

You may already know that a tire's name is made up of a mess of letters and numbers; you probably are aware that all the letters and numbers do in fact mean something, but you are just not sure what. In this post, I will explain the method to the madness and hopefully teach you how to read the name of a tire.

The First Letter

If the first letter is P (meaning p-metric), you know that the tire is designed to be used on passenger vehicles, which includes car, minivans, station wagons, sport utility vehicles, crossovers, and 1/4 tonne to 1/2 tonne trucks.

If there is no letter at the start of the name, the tire is Euro-metric. This is generally found on European vehicles, as well as SUV's and minivans. They only difference you should take into account is the load capacity, which may differ slightly from p-metric tires.

If the first letter is T, then the tire is temporary, or in other words, a spare, and should only be driven on until you can have a suitable tire fitted.

If the first letters are LT, you know that the tires are light truck metric, and made for vehicles that can handle heavy loads from 3/4 to 1 tonne.

If the first letters are ST, you have yourself a special trailer tire. These tires are designed for trailers only, and should not, under any circumstances, be used on passenger vehicles.


The Last Letter

If a tire ends with LT, the tire is designed for heavy loads and large vehicles. Unless you use heavy equipment regularly, you should not have to worry about this labeling.

If a tire ends with C, it is a commercial tire designed for large box trucks, and once again, if you are not in the business, you should not have to worry about this.

The Three Number Chunk

The three numbers represent the width of the tire in millimeters from one side of the tire to the other (measured from the furthest points along the side, not on the tread).

The Two Number Chunk

This number represents the relation between the sidewall height and the tread width expressed as a percentage. For example, a tire with a width of 250 mm and a percentage of 50 leaves us with a sidewall height of 125 mm. The sidewall is the side of the tire from the outer edge (that touches the ground), to the inner edge (where the rim is).

The Next Letter

This letter represents the construction of the tire. R is the most common, meaning radial. To put it simply, the tire is designed so that the tread radiates out from the center as the tire rotates. The only other letter you are likely to see is D, meaning diagonal. These are common on small trucks and spare tires.

More Numbers

This represents the size of the wheel in inches that your tire should be fitted on. A tire with the number 16 here is designed to go on a 16 inch rim.

If you can have a general idea of how the naming of a tire works, doing business with tire dealers will be that much easier.