Tyre Glossary: 40 Terms To Know About Tyres

Tyre Glossary: 40 Terms To Know About Tyres

Tyre | 30 January 2019

Posted by Paul Burlington

Tyre Glossary 40 Terms to Know about Tyres UK

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

A

Asymmetrical Tread

A unique tread pattern on the tyre that allows for maximum grip on both dry and wet roads. The pattern on the outside of the tyre 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 tyre’s section height as compared to its section width. It’s the two-digit number after the slash mark in the tyre size code. For example, a tyre sized P215/65R17 has a tyre aspect ratio of “65,” meaning that the height is equal to 65% of the tyre’s width. The larger the aspect ratio, the larger the tyre’s sidewall will be.

B

Bead

A rubber coated round loop of steel wires that connects the tyre 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 tyre tread and the body plies. Belts provide stability and strength to the tyre’s tread area, which helps puncture resistance.

Bias Ply Tyre

Inside a bias ply tyre, 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

Carbon Black

Used as a reinforcing filler in tyres that can be combined into the rubber compound. It helps conduct heat away from the tread and belt area, which gives the tyre 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 tyre.

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 tyres that signifies that the tyre 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 tyre size, type, manufacturer, manufacturing location, etc.

E

ETRMA

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

G

Green Tyre

A tyre that has not been cured or vulcanised.

Grooves

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

L

Light Truck Tyres

Tyres 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 tyres durable and rugged, perfect for harsh road conditions.

Load Index

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

M

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

Also called all-season tyres, these tyres have the letters M+S on the sidewall. These letters indicate that the tyre 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 tyres on a brand new vehicle that were chosen by the manufacturer to provide the performance characteristics they desire.

P

Passenger Tyres

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

Performance Tyres

Tyres 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 tyre.

Pneumatic Tyre

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

R

Radial Tyre

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

Ribs

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

S

Service Description

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

Shoulder

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

Sidewall

The side of a tyre between the tread and the bead. You can find important tyre information located on the sidewall including the tyre 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 tyre’s sidewall that identify the tyre’s width, aspect ratio, wheel diameter, and construction type. For example, a tyre size of 215/65R17 87S tells you that the tyre 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 tyre can travel safely.

Symmetrical Tread

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

Synthetic Rubber

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

T

Tyre Hospital

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

Tread

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

Tread Depth

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

U

Ultra High Performance Tyres

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

UTQG (Uniform Tyre Quality Grade)

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

V

Vulcanisation

The process of heating rubber under pressure to fuse the tyre’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 tyre experts and they’ll answer any additional questions you might have.

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Paul Burlington

Paul Burlington is Computype’s Director of Business Development. Having worked directly with our customers for over 30 years, he has a deep understanding of the needs and challenges our customers face—specifically those working in industrial environments. Paul is our go-to-guy for all things tyre and rubber belt related, whether that means product ideas or efficiency boosting advice. Outside of work he enjoys spending time in the great outdoors.