What information lies within a tire size?

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P225/75R16 95H

Lets start from the beginning.

The first letter or letters in your tire size correlate to what type of tire it is. For example P stands for passenger & LT stands for light truck. Here at Georgica Services these are the tires we deal with.

The following three digit number, in this case 225 – is the tire width in mm. This is measured from sidewall to sidewall. The next two numbers after the backslash represent the height of the tire. It is also refered  to as the tire aspect ratio, or the ratio of the tire height to it’s width. In the our example the aspect ratio is 75 so the height of the sidewall is equal to 75% of the width.

The next letter tells the type of construction. In most cases the letter is R and it is a radial tire.

The next two numbers are the wheel diameter. In the above case 16, this tire fits on a 16″ wheel.

95 is the load index of the tire and means this tire will bear 1521 pounds when properly inflated.   A tire with a load index of 96 supports 1565 pounds.

The next letter tells you the speed rating of the tire.  An H rated tire tells us that tire is certified to 130 mph.  A T rated tire is certified to 118 mph .

Elsewhere on the tire you will find Treadwear, Traction and Temperature ratings, the maximum cold inflation pressure, and the tire construction specs.

The DOT serial number system is stamped on the side of the tire, for example:

DOT MA L9 ABC 0310

DOT tells you the tire meets or exceeds the Department of Transportation safety standards. MA is the manufacturer and plant code, L9 is the tire size code number, ABC is a group of optional symbols for the manufacturer to use in identifying the brand or other significant characteristics of the tire. The last four numbers are the date code. The first two numbers indicate the week the tires were made, and the last two are the year after 2000. If you have a three digit date code, your tires were made before that year.