What Do The Numbers On Tires Mean?

Tires have a lot of info. The size is just one bit that you'll need to know about the tire. The "P225/45R17 91V" may not mean anything now, but it says a lot to experts about the type of tire and how they are made. There are different types of tires and sizes, but we can explain each one by using this guide.

Tire service type ratings

Most car tires have letters at the beginning. Like P or LT. That tells us what type of vehicle the tire was made for.

P = P-Metric (Example: P215/65R17 98T)

P-Metric tires are the most common type of tire. Passenger vehicles use these tires. That means they are good for cars, minivans, light-duty pickup trucks (? ton or ? ton capacity), and SUVs.

Metric / Euro-Metric (Example: 185/65R15 88T)

Metric tires are also called Euro-Metric tires because they were invented in Europe. They have the same dimensions as P-Metric tires, but they are made for different things. Euro-Metric tires are usually found on cars from Europe, but they're also used on SUVs and vans a lot.

LT - Light Truck (prefix) (Example: LT235/75R15 104/101S/C)

Light Truck Metric tire sizes start with the letters LT. These tires are designed for use on vehicles that tow trailers or carry heavy loads. This includes SUVs, full-size vans, and medium-duty and heavy-duty pickup trucks with? ton to 1-ton capacity.

LT - Light Truck (suffix) (Example: 9.5-16.5 LT121/117R)

These tires are made for light-duty, medium-duty, and heavy-duty pickup trucks, sport utility vehicles, and vans.

T = Temporary Spare (Example: T145/70R17 106M)

If the tire size starts with a T, it means that the tire is for a temporary spare. Temporary spares are mini spares or space savers that are designed for short-term use until the regular tire is repaired or replaced.

ST - Special Trailer (Example: ST175/80R13)

ST tires are special trailer tires that should only be used on car, boat, or utility trailers.

C = Commercial (Example: 31x10.50R15/ C109R)

Commercial tire sizes that end with a C are for delivery trucks and vans that can carry a lot of weight. The tire size is also marked with how much weight it can hold (load range B, C, or D).

Tire Sizes Explained

Section width of tire (Example: P 225/45R17 91V)

The tire has numbers. The tire is for cars and trucks, and it is about as high as your knee. The tire has three digits following the service type prefix (if present) tell us the cross-sectional width of the tire in millimeters."

In this tire example, there are 225 millimeters of width from the widest point of one side to the widest point on another side when properly mounted." To find out how wide it is in inches, convert with tire size chart.

Aspect ratio of sidewall (Example: P225/ 45R17 91V)

The number that usually follows the tire's section width tells us the aspect ratio. This is a measure of how tall or short the sidewall is. In this example, the 45 means that the sidewall distance, from the wheel rim to the outside of the tread, is 45% of the section width.

A lower aspect ratio tire will have a shorter sidewall, while a tire with a higher aspect ratio will have a taller sidewall. Because we know that the tire size shown in this example has a section width of 8.86 inches and an aspect ratio of 45%, we can calculate that the sidewall height for this tire is 3.98 inches: (8.86 inches) x (.45) = 3.98 inches.

Tire and wheel diameter (Example: P225/45R 1791V)

The number "17" on a tire means that the tire should be matched to a wheel that is also 17 inches in diameter. Tires usually come in widths of 8, 10, 12, 13, 14, 15, 17, 18, 19, 20, 22, 23, 24. Some tires are also made in 26 and 28 inch sizes.

Unique wheel diameters

There are different tire sizes that are not as common. They have a half inch diameter and they are for heavy-duty light trucks, box vans, and heavy-duty trailers. There are five different sizes: 14.5, 15.5, 16.5, 17.5, and 19.5 inches in diameter. An example of this size is 33x12.5R16.5 118R tire size. You should always confirm the tire and wheel diameters match before mounting tires on wheels.