When you look at your tires you will notice several sets of numbers on them. These are groups of several letters and numbers which will be meaningless to you, particularly when you are not involved with tires.
However, the numbers provide significant information about your tires and may be of great assistance when you need to inflate them or when you are purchasing new tires.
Let’s take a look at a car tire number and decipher it.
The number is P235/75 R 15 89H.
The first letter, in this case “P”, refers to the type of tire. The letter P designates your tire as one for a passenger vehicle. Other letters you might find include T for temporary or spare tire, or LT for light truck.
The second number, in this case “235” is the tire width as measured in millimeters from one edge of the sidewall to the other. A good rule of thumb is that the larger the first set of numbers are, the larger the tire size is.
The number 75 refers to the section height or aspect ratio of the tire. You will see the numbers are listed as a ratio 235/75, indicating that the height is 55% of the width The designated purpose of the tire is revealed by this tire number. A lower number indicates that this is a short sidewall, giving better steering and handling in general.
The next position, “R,” shows that the tire is of radial construction. The radial tire is the most common kind of tire made.
The number 15 gives you the diameter of the rim, as measured in inches. This number is particularly important when you need to make a change in the size of your wheel.
The next number, “89,” indicates the load index of the tire, or the amount of weight which can be supported. That is, the greater this number, the heavier the load that may be supported. In P235/75 R 15 89H, the 89 states the tires can bear 1,260 pounds.
The letter “H” corresponds with the speed capacity of your car tire. An H in this case shows a maximum speed of 130mph on these tires. H is only one of many different letters assigned for various speed capabilities on tires.
If you want to purchase the most appropriate tires for your car, it pays to get to know these numbers.
Filed under: Truck Tires
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