Tires have a lot of information on the sidewalls. Unfortunately, it is all code. While most of this information is not of concern to most owners, it can be useful for those who need to know the season for which their tires were made, for those who plan on replacing their tires, and for new-car buyers who have the option of choosing from a variety of sizes.
The most prominent marking on a Honda Civic is the one that includes the name of the manufacturer and model of the tire — Bridgestone Turanza EL 400, for example — as follows.

This is a passenger-car tires. Other codes include P (passenger-car tire), LT, light truck and C (commercial). This letter is not required for all tires.

The tire’s width measured in millimeters is 205 (the first number).

55 (the number after the slash is the tire’s profile) is the height of the tire’s sidewall relative to its width. This can be expressed as the sidewall aspect ratio in percentage. The tire’s width is 205mm. In this case, 55 percent of its sidewall height is used. This number is called the tire’s series. A sporty tire would have shorter sidewalls and be classified as a lower-series. Off-road tires are usually higher-series and are designed to absorb impact from rough surfaces.

R is for radial tires. This refers to the way that the underlying layers or plies are laid out. Radial design is so common that the R designation has become redundant. However, it does allow you to distinguish the series numbers and the diameter numbers. An additional letter is added to the R on some performance tires. A ZR designation indicates that the tire’s maximum speed rating exceeds 149 mph (see key below). This is an unnecessary character. All tires have a letter designation in their service description. Sometimes it is in smaller font.

Speed Ratings Letter / Max. MP


N/87

P/93

Q/99

R/106

S/112

T/118

U/124

H/130

V/149

W/168

Y/186

Z*150

*Z refers to an open-ended rating. It means that the tire’s maximum speed is at least 150 mph.

16 is the last number. This refers to the size of the tire’s rim in inches.

The service description is 89H. It is separate from the main code and represents the tire’s speed ratings and load. The tire’s 89 load rating is 1,279 pounds per tire, and the H speed rating is 130 mph. In the United States, speed ratings are less important because the speed limits are lower than the listed rating (N or 87 mph). People are known to drive at least 100 mph in other countries, as well as ours when nobody is looking.

This tire is also known as M+S, which stands for mud-and-snow. This is not the most clear of specs because there are no other designations for summer or winter tires. Summer tires lack the M+S while winter tires have the M+S. Winter tires add the icon of a mountain covered with a huge snowflake. (S, AS, and W would be better but it’s what you have to do). Uniform Tire Quality Grading The three codes that appear on the sidewall of tires are usually closer to the tread and part of the National Highway Traffic Safety Administration’s uniform tire-quality rating system. However, the code is not uniform. It can be found on all-season tires and summer tires but not on snow tires, light truck tires or spares. The rating is determined by the manufacturers. While the results may be consistent between products, their universality is not.

TREADWEAR 300 TRACTION A TEMPERATURE

Treadwear: There are a variety of uses for treadwear, ranging from 100 to 700. A tire rated 150 will have a 50% longer life span than a tire rated 100, provided it is used under the same conditions as drivers, vehicles, and roads. All-season tires have higher treadwear ratings than soft summer tires. Although winter tires are not rated, their soft compounds can be worn quickly when driving on snow or ice.

Near the tread, the sidewall shows the uniform tire quality grade. Traction: Uses A, B, and C. AA is the best for traction on wet roads. Straight-line acceleration and brake are the best measures of traction. This does not include cornering grip, or performance on wet surfaces.

Temperature: There are three letter grades for temperature, A, B, and C. A is the most resistant to heat buildup, and C is the least. Heat is generated by the friction of a tire against pavement. Too much heat can cause high-speed performance to be degraded and accelerate aging. The lowest possible rating is C. The temperature ratings correspond to speed. C represents speeds between 85 and 100 mph, B represents speeds between 100 and 115 mph, A covers speeds over 115 mph.

Notes: The temperature rating, like the “Z speed rating”, is redundant because it’s tied with a speed rating that’s more specific in the service description. It’s better to not buy replacement tires with lower ratings than the originals. Also, it’s easier to match one of the three temp ratings to the originals than to match the 11 speed ratings listed in the service description.



Because of the critical role played by where and how people drive, it’s difficult to convert treadwear ratings into miles. If you feel your tires are wearing out too quickly, consider upgrading to a higher rating. This is true for traction as well. However, it is important to understand that changes in one aspect can affect others such as treadwear, noise quality, or price.
Date of manufacture/tire age
The Department of Transportation’s tire identification number is different from other more prominent specs. It includes the week and the year of the tire’s manufacturing and its age. Safety has been a concern because tire age is more than just wear.

The TIN is located near the rim and consists of a number of numbers and letters that are similar to a vehicle identification number. The last four numbers are the year and birth week of any tire manufactured after 2000.

DOT H25R 4305

This tire was made in the 43rd Week of 2005. Tires made before 2000 had a three-digit code. The year was then reduced to one. It would have been 437 if the tire was from 2005. Could 437 also refer to a tire that was made in the 43rd Week of 1987? It would, unfortunately. That’s why the four-digit code is used.

Recent concerns have been raised about the impact of tire age on safety. There are not universal guidelines for aging because climate and how well a tire has been maintained can affect it. While most tires last six years, some automakers, mainly German ones, recommend that they be replaced regardless of wear. Automakers generally agree that 10 years is the safest lifespan for tires, even if they have never been used. It is a good idea to verify the tire’s birth date before purchasing new tires. They should be treated like milk. Your family may finish a gallon of milk before the expiration date. Don’t take a chance. You should also get the best milk and tires for the same amount of money. Although you might use the tires long before their due date, why not buy a set that is already in motion?

What’s not on the Sidewall? The proper Inflation Pressure

You will likely find the maximum pressure figure on a tire’s sidewall if you look carefully enough. Don’t do it. This is not the recommended pressure to use. It’s the maximum tire rating, regardless of what vehicle it’s on. It’s almost always significantly higher than what you should be using.

As required by law, new cars have the correct inflation pressures on their driver’s doorjamb. See Tire Maintenance for more information.

(C) 2013, Cars.com. Distributed by Tribune Media Services