A tire is an integral part of your vehicle. I noticed that my tires are starting to get worn down and will soon need to be replaced. It’s helpful to have some knowledge about what exactly you’re getting in a tire before you buy them.
When you have a careful look at the tire of your car, you will notice that there are numbers across the side wall of the tire. These numbers indicate:
- The tire size (width/height/rim it will fit – such as 215/45R17)
- The load a tire can take – (such as 87)
- The speed at a tire can go – (such as H)
Maybe you need to balance your car tires or take care of a flat. Knowing about the tire number may be helpful. Each number and letter shows a specific detail about your tires. Let’s find out what each means.
What do the Car Tires Numbers Mean?
Photo Credit: http://www.continentaltire.com/news/how-read-tire-sidewall
When you have a look at the tire of the car, you will notice that the numbers are written in the following pattern P215/65R15 in the following picture. You’ll notice that the number refers to the width, height, and diameter of the tire.
First Letter of Your Car Tire
The first alphabet on the tire can be P, LT, ST, or T. Sometimes there is the absence of the first alphabet. The first alphabet denotes:
- P: Passenger car and it indicates that the tire is the P-metric type. The vehicles that are perfectly suitable for such tires are either lightweight trucks or cabs. These types of tires are widely in use.
- LT: Light Truck types of tires are usually recommendable for heavy-weight vehicles like sports utility vehicles or heavy-duty pickup trucks. The design of these tires enables them to easily bear all types of additional weight that are put on them.
- ST: Special Trailer types of tires are only for special vehicles like boats or aircraft. It is highly advisable not to use these tires for small and lightweight vehicles.
- T: Temporary types of tires are especially for spare tires only. You can make use of these tires when you need to replace a car tire.
When there is an absence of an alphabet before the three-digit numbers, then it indicates that the tire is of metric type.
Meaning of the Three-Digit Tire Number
The three-digit number after the first alphabet indicates the cross-section width of the tire. The unit of quantity is usually in millimeters.
For instance, if the first three digits are 247 then it is appropriate to say that the cross-section width of the tire is 247 millimeters.
Meaning of the Two-Digit Tire Number
The two-digit number after the three-digit number, separated by an oblique, indicates the aspect ratio of the tire. The aspect ratio is regarding from the rim of the tire to the head of the tire.
For instance, if the two-digit number after the three-digit number is 60, then it is much more appropriate to say that the side wall of the tire of the car is 60% of the cross-section width of the tire. It also denotes that the higher the aspect ratio, the taller will be the sidewall of the tire.
In some tires, there might be an absence of the two-digit number. In such cases, you can consider the aspect ratio to be 82%.
Tire Letter Meaning
The alphabet after the two-digit number provides an indication of the internal construction of the tire. The alphabets are R, B, or D.
- R: R indicates the radical design of the tire that is highly common nowadays.
- B: If the next alphabet is B, then it means that there is a presence of a belt beneath the strand vicinity of the tire. These designs are now out of fashion and no longer in use.
- D: If the alphabet is D then it means that the tire is moving internally in a diagonal manner. This type of design is mostly for either lightweight trucks or spare tires.
Meaning of the Two-Digit Tire Number After Letter
The two-digit number that is after the R (or other letters) on the tire refers to the diameter of the rim. The measurement of the diameter of the rim of the tire is in inches.
The different size diameters that are available are:
- 8, 12, 13, 14, 15, 17, 18, 19, 20, 22, 23, 24, 26, and 28.
These rims come on many types of vehicles, from lightweight trucks to sport utility cars.
For instance, if the two-digit number is 16 then you would need to get a tire that can fit on a 16-inch rim.
Meaning of the Two-Digit Number With Letter
The combination of the two-digit number and the letter indicates the load a tire can take and the speed that it is rated for. This combination also helps in recognizing what might be too heavy and too fast for your tires.
In the picture below the load rating is 82. This means the tire can handle 1047 lbs and four tires together can handle about 4188 lbs. If the rating is higher than 82 the tire can handle more than 1047 lbs, and if it’s lower it can handle less.
The letter S means the tire can handle 112 mph. The speed rating goes up starting from A through Y, although a couple of letters like H for 130 mph (as seen in the picture above) are out of order and represent various mph.
Photo Credit: http://www.wheels.ca/guides/torque-mean-gearhead-terms-explained-2/
The more you know about the details of your tires, the better choices you can make for your car. It is important that you buy the correct tire for your vehicle by inspecting the tire’s numbers and letters before you decide to buy a new set of tires.
I hope this guide is helpful in getting to know more about your tires. Next time you buy some tires you can decide with more expertise and know exactly what many of the different numbers on the car mean.
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