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Tire Glossary: 40 Terms To Know About Tires

Tire Glossary: 40 Terms To Know About Tires

Tire | 30 January 2019

Posted by Simon Boddy

 Tire Glossary 40 Terms to Know about Tires

Not sure how to interpret all the tire lingo the auto service technician uses? Getting frustrated shopping for tires because you don’t know what any of the specs actually mean? You’re in the right place. With our conveniently alphabetized glossary, you will be fluent in tire terminology in no time! 

A

Asymmetrical Tread

A unique tread pattern on the tire that allows for maximum grip on both dry and wet roads. The pattern on the outside of the tire is made up of large tread blocks to create a bigger contact patch to handle dry traction. The inside and middle pattern features smaller tread blocks and grooves to improve grip when dealing with wet and winter traction.

Aspect Ratio

This number describes the tire’s section height as compared to its section width. It’s the two-digit number after the slash mark in the tire size code. For example, a tire sized P215/65R17 has a tire aspect ratio of “65,” meaning that the height is equal to 65% of the tire’s width. The larger the aspect ratio, the larger the tire’s sidewall will be.

B

Bead

A rubber coated round loop of steel wires that connects the tire to the rim.

  • Bead Chafers: Protects the wire bead components from damage

  • Bead Chipper: Reinforces the lower sidewall

  • Bead Flipper: Helps keep the bead in place

Belts

Most commonly made up of rubber-coated layers of steel cords and located between the tire tread and the body plies. Belts provide stability and strength to the tire’s tread area, which helps puncture resistance.

Bias Ply Tire

Inside a bias ply tire, cords (usually made of a fabric like nylon, polyester, or rayon) are layered in a crisscross pattern, running from bead to bead. This pattern provides extra strength and greater puncture resistance in the sidewall.

C

sidewallCarbon Black

Used as a reinforcing filler in tires that can be combined into the rubber compound. It helps conduct heat away from the tread and belt area, which gives the tire higher resistance to wear.

Carcass Ply

Made up of thin textile fiber cables bonded into the rubber, the carcass is the supporting structure of a tire.

Contact Patch

The tread portion that comes into contact with the road while driving.

D

Dot Markings/ D.O.T. Number

A code branded on the sidewall of tires that signifies that the tire has passed all the tests required by the Department of Transportation for safety standards. The code begins with the letters “DOT,” and may contain 10-12 characters that provide information like tire size, type, manufacturer, manufacturing location, etc.

E

ETRMA

European Tire and Rubber Manufacturers’ Association – provides guidelines and recommendations for tire and rubber goods producers in Europe.

G

Green Tire

A tire that has not been cured or vulcanized.

Grooves

Spaces between the tread ribs of a tire. The grooves in the tread are designed to allow water to escape easily and prevent hydroplaning.

L

Light Truck Tires

Tires designed to be used on vehicles that are capable of carrying heavy loads or towing large trailers, such as pickup trucks, vans, and SUVs. The higher load carrying capacities make these LT tires durable and rugged, perfect for harsh road conditions.

Load Index

An assigned number associated with the amount of weight a tire can carry that varies from 0 to 279.

M

Mud and Snow (M+S, M/S, M&S)

Also called all-season tires, these tires have the letters M+S on the sidewall. These letters indicate that the tire tread is specifically engineered to function well in slick or slippery conditions. 

N

NHSTA

National Highway Traffic Safety Administration – responsible for keeping people safe on America’s roads.

O

Original equipment (OE)

The tires on a brand new vehicle that were chosen by the manufacturer to provide the performance characteristics they desire.

tire formationP

Passenger Tires

Tires used by vehicles that carry lighter loads. These tires are usually the default tires on most vehicles, making them affordable and easy to find.

Performance Tires

Tires designed to give sports cars and other vehicle owners improved handling, the ability to stop shorter, and higher speed capabilities.

Ply/Plies

Running from bead to bead, plies are rubber-coated layers of fabric containing cords that make up the inside structure of a tire.

Pneumatic Tire

A tire filled with compressed air used on many standard vehicles.

R

Radial Tire

In a radial tire, cords (usually made of steel) run through the inside of the tire horizontally from bead to bead. These crisscrossing steel belts beneath the tread increase structural integrity.  

Ribs

The pattern of tread aligned around the tire’s circumference. There are usually multiple ribs molded across a tire’s tread.

S

Service Description

Characters molded into the sidewall that identify the tire’s load index and speed rating. For example, a tire sized P215/65R17 87S has a service description of 87S. The 87 represents the tire’s load index and the S identifies the tire’s speed rating.

Shoulder

The outer edge of the tire’s tread where it meets the sidewall.

Sidewall

The side of a tire between the tread and the bead. You can find important tire information located on the sidewall including the tire size, construction, date of manufacture, etc.

Sipes

Small, narrow slits in a tread block that increase traction for driving in snowy, wet or icy conditions.

Size

The letters and numbers on the tire’s sidewall that identify the tire’s width, aspect ratio, wheel diameter, and construction type. For example, a tire size of 215/65R17 87S tells you that the tire has a width of 215 millimeters, an aspect ratio of 65% and a wheel diameter of 17 inches.

Speed Rating

A letter code identifying the maximum speed at which a tire can travel safely.

Symmetrical Tread

A tread pattern that is the same on both sides of the tire. A symmetrical tread pattern uses continuous ribs or independent tread blocks across the whole tire.

Synthetic Rubber

Rubber created from chemicals as a substitute for natural rubber. Currently, most tires are made of synthetic rubber, with very little natural rubber in their construction.

T

Tire Hospital

A term used by tire manufacturers to describe the area where tires which haven’t met quality standards are sent. The tire hospital typically involves rework and additional quality checkpoints.

tire no backTread

The outermost layer of a tire that comes into contact with the road surface.

Tread Depth

The measurement from the tread surface to the bottom of the tire’s tread grooves. This is measured in 32nds of an inch. Tires are considered legally worn out at 2/32”.

U

Ultra High Performance Tires

Designed to handle the extra horsepower of sports cars. UHP tires provide high-speed stability and prime cornering response.

UTQG (Uniform Tire Quality Grade)

Provides consumers with useful information when purchasing tires. This information is a performance rating of tires' traction, treadwear, and temperature resistance.

V

Vulcanization

The process of heating rubber under pressure to fuse the tire’s various components together, which gives the rubber increased strength and elasticity.

Is the word you were looking for not in our glossary or maybe you’re still confused about one of the terms? No worries, we are here to help! Click here to reach out to one of our tire experts and they’ll answer any additional questions you might have.

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Simon Boddy

Simon Boddy is Computype’s Global Product Manager within our Industrial Business Unit. Based in our UK facility, he has worked closely with many global tire manufacturers to improve their processes and ensure accurate bead and tread labeling. Most recently, Simon played a large role in launching Computype’s new automated tread labeling system, Chromaffix.