What Do The Tire Size Numbers Mean

Tires take several numbers and symbols on the sidewall, and they tin can exist a little mysterious if you don't know their significant. Each number and symbol has specific meanings, and plus there are other key elements you should know about your tires!

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Tire Size Meaning

What do all the numbers and symbols mean? Here is a guide to understanding tire size meaning.

Where to observe tire size

Every tire has 3 numbers that mean a specific size:

The first number measures the width and it looks something similar this: [205/65 R 15]. The 205 on the tire means it is 205 millimeters wide looking at the tire head on.

The second number, 65, is the attribute ratio, which means that the height of the tire is 65% of the tire's width for this example. The bigger the aspect ratio, the larger the sidewall of the tire.

The last number, 15, is the rim diameter of the wheel that the tire volition fit.

The tire letter meaning refers to the construction of the tire: R for radial, D for diagonal, and RF for run-flat.

How to find load alphabetize

Next to your tire size you volition come across a number and letter combination like 94H. The number "94" is the load index. This is the number relative to the weight capacity of the tire. The college the number, the greater the load carrying capability of the tire. Load index ranges from 0 to 150.

If you are replacing your tires, they accept to be the same or higher load alphabetize, never lower. For example, if your current load index is 103, a tire of the same size with a load index of 112 would work for you, but not a tire of the same size with a load index of 94. If you replace your tires and the new ones accept a lower load index, the tire has a high likelihood of bubbling and somewhen blowing out.

How to find your tire's speed rating

Side by side to the load index in that location is a letter. In the example mentioned above, the "H" is the speed rating. This is the maximum speed sustainable for the tire. Each letter has a corresponding speed rating approved by the DOT (Department of Transportation) and the tire manufacturer.

Alphabetically, the speed rating increases equally the letters advance A-Z -- EXCEPT for the letter H, which we'll explain in a infinitesimal. The well-nigh common speed ratings range from L (75 MPH) to W (168 MPH). Loftier-performance racing tires speed rated 168 MPH or higher are marked ZR.

Originally, tire speeds were simply S, H, or V (Due south beingness the slowest, H existence the center, and V being the fastest); over the years as tire speeds take evolved, for whatever reason, H has always remained the same, 130 MPH.

How to find week and year of production

Your tires have a number that indicates when the tire was fabricated. This identification tin exist idea of as somewhat of a birth certificate for your tire. Beginning with DOT at that place is a combination of letters and numbers that will end in a 4-digit numerical code. For example, if your tire reads [DOT CPEX 3ET 0311] the tire was made during the 3rd calendar week of the twelvemonth 2011. In the instance above, the tire was made in the terminal week (52) of 2010. DOT signifies that the manufacturer has complied with the Section of Transportations tire prophylactic standards.

Tire Letter Meaning

Additionally you volition find letters and symbols that tell you more than about the tires, although not all tires accept the following letters and symbols.

Three-peak mountain snowflake (3PMSF)

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If you lot see the three-elevation mountain snowflake symbol on the sidewall of your tire, this indicates that they are rated for severe snow and ice. The symbol is identified by a snowflake surrounded by a 3-peak mountain zig-zag shape. If your tire has the 3PMSF symbol it meets the requirements of snow traction performance and has certified approving for severe winter conditions.

E-marking meaning

The East-mark, plant on the sidewall of the tire designates that the tire meets the minimum Eu and international standards relating to the size, load index and speed rating of the tire. This mark confirms that testing has met acceptable performance regulations. Non all tires sold in the U.S. have an Due east-mark.

S-mark significant

The S-marking, also institute on the sidewall, means that the tire has met "sound blessing" relating to the road racket produced by the tires. All new tires produced since 2011 must accept an S-Marking rating to exist sellable past retailers in compliance with EU standards. Not all tires sold in the U.South. have an S-mark.

Tire Size Definitions

What does the P represent on tires?

P on a tire stands for passenger and ways the tire was designed to be used on motorbus types.

What does LT mean on a tire?

LT on a tire stands for light truck and means the tire was designed to exist used on low-cal and heavy-duty selection up trucks.

What does ST mean on a tire?

ST on a tire stands for special tire and ways that the tires are designed for towing trailers with non-powered axels.

What does R17 mean on a tire?

R17 on a tire means that the rim size needed would exist 17". The "R" actually stands for radial, not rim and is the type of applied science the tire uses.

What does the Z mean in tire size?

The Z ways that the tire has been tested over 186 mph

What does the R stand for in tire size?

The R on a tire stands for radial and refers to the blazon of applied science beingness used within the tire.

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