This should help. Section "G"
is the DOT code that will tell you the date your tires where manufactured.
The largest markings on the tire will tell you either the Brand name and/or the Manufacturer of the tire and the Model or Design name or number. Some companies number their different designs, others use names for their designs, and others will combine the two.
A series of numbers and letters similar to 185/65R13 96H as shown in our example or 195/70R14 gives you the most used information about your tire. The sequence is broken down into the following parts:
185/ The numbers before the slash mark tell you the width of the tire at its widest part when mounted on a wheel and inflated to the recommended pressure but without any weight on the wheel, measured in millimeters. This sequence will almost certainly be three digits and will likely range from about 155 to over 300. Unless vehicledesigns change drastically we're not likely to see anything out of this range.
65 Following the slash will be a 2 digit number which is a percentage, most likely between about 50 to about 80 percent. (It could be as high as 200 but that is highly unlikely.) This percentage is called theAspect Ratio. If you multiply the width (the first number) by the aspect ratio number, the result will tell you the height of the tire section between the bead and the tread. In our example number we multiply 185 x .65 and cancalculate that this tire has a height of 120.25 mm.
In some countries the number may be more than 200, in which case it is the actual height measurement in millimeters, instead of a percentage.
R Next there will likely be the letter "R" which informs you that the tire is of Radial construction. In very rare instances the letter might be a "B" or not be present at all, indicating that the tire is a Bias-Ply type of tire.
13 Following the "R" or space will be a two digit number which is the diameter of the wheel in inches which this tire is designed to use. This example is for a 13 inch wheel. Wheel ranges today range from 10 to about 20 inches for cars and even larger for trucks and busses.
96 These numbers following the wheel diameter do not appear on all tires, but if they do they are a code for the maximum weight which that tire is designed to support.
H The final letter is a code for the speed rating of the tire. This code tells you what is the maximum sustained speed which this tire is designed for. In some cases this letter might precede the "R" which designates that the tire is a Radial tire (noted above).
The word RADIAL (in addition to the preceding code, informs you that the tire is of Radial construction. You may also find the word TUBELESS nearby which means that the tire is designed to be used without an inner tube.
M&Smeans this tire is designed for Mud and Snow driving. This will only appear on tires designed for such use. REINFORCEDalso only will appear if the tire has extra reinforcement not normally found in a tire of its type.
MAXIMUM PRESSURE 40 psi is the maximum tire pressure (in pounds per square inch) which this tire is designed to support. This pressure should be measured when the tire is cold, and never exceeded. However, this is not the ideal pressure for best driving performance. Recommended pressure is set by the car manufacturer, and should always be less than the maximum printed on the tire. If the car manufacturer recommends more, then a different tire should be used.
European tire registration Number. All tires which are for sale in Europe since 1997 must carry this number which begins with an upper or lower case "E". The next two digits are a code which designate the country which issued the approval certificate and the last sequence of numbers is the actual registration number for that specific tire model.
US Department of Transport code. This code is required on all tires which may be sold in the USA. Following the "DOT" the code uses the format: XXXX XXXX XXXXin which the first two letters designate where the tire was manufactured. The next two letters and numbers are a code for the tire size and the following 4 are for discretionary use by the manufacturer and may be omitted. The final group of four tells you the week and year in which the tire was manufactured. "2206" would indicate a tire made in week 22 of the year 2006. Before the year 2000, this part of the code was only 3 digits long, for example 019 would be on a tire made in the first week of 1999.
Some tires do not have the COMPLETE DOT code on BOTH sides of the tire. If you do not see 11 or 12 characters following DOT, you may have to look on the other side of the tire.
To decode the 3rd and 4th characters, which tell the tire size see the DOT Tire Size Chart.
Other information may also be printed on tire sidewalls. The country of manufacture may be printed. The temperature rating of the tire may be included which gives you some idea of how the tire resists heating which occurs when driving at high speeds for extended periods. The best rating is the letter "A", while "C" is the lowest.
A traction rating which measures the car's handling on wet roads runs from "A" to "C" which, like the temperature has "A" as the best level.
A tread wear rating may appear. This indicator is not standardized and may vary from one manufacturer to another because each may establish differentmeasurements to reach the rating. What this can tell you is that a tire made by company "A" which has a rating of 200 will probably last about twice as long as a tire from that same company with a rating of 100. You cannot use the same ratio for comparing tires of Company "B" to Company "A". Our guide to using tread wear may be of some use to you.
These explanations are valid for tires in general use and manufactured since the year 2000. Older tires and models which may be used on classic, antique or vintage cars may use different measurements that are no longer relevant.
Load Range, Ply Rating and PSI for Light Truck Tires
D - 8 ply - 65 psi
E - 10 ply - 80 psi
F - 12 ply - 95 psi
B - 4 ply - 35 psi
C - 6 ply - 50 psi
D - 8 ply - 65 psi