Technical Dictionary

T & RA

Tyre and Rim Association.

Tensile Strength

An object’s resistance to stretching or breaking when placed in tension. Steel belts in a tyre are characterized and compared based on their tensile strength.

Toe

The difference in distance between the front and rear of a pair of tyres mounted on the same axle.

Toe-In

The fronts of two tyres on the same axle are closer than the rears of the tyres.

Toe-Out

The fronts of two tyres on the same axle are further apart than the rears of the tyres.

Toe-Out Turns

Also known as Ackerman Angle. A vehicle’s wheels on the inside of a turn follow a smaller radius than the tyres on the outside of the turn, because the two front wheels steer at different angles when turning.

Torque

Turning or twisting effort, usually measured in lb-ft or Newton meters.

Torque-Locking Sipes

Sipes with vertical undulation (into tread block) for added rigidity during cornering.

Torsion Bar

A long, straight bar fastened to the frame at one end and to a suspension part at the other; acts like an uncoiled spring that absorbs energy by twisting.

Touring Tyres

Generally offer increased tread life, comfort, and all-season traction.

Track

The distance between the outside tread edges of two tyres on the same axle.

Traction

The friction between the tyres and the road surface; the amount of grip provided.

Tramping

A state in which a vehicle bounces up and down abnormally.

Tread

That portion of a tyre that comes into contact with the road. It is distinguished by the design of its ribs and grooves. Provides traction in a variety of conditions, withstands high forces, and resists wear, abrasion, and heat.

Tread Buffing

Scraping rubber off the tread. Also known as shaving.

Tread Depth

The depth of usable tread rubber measured in 32nds of an inch. If a tyre comes new with 10/32nds of rubber, you have 8/32nds of usable rubber. Tyres must be replaced when the wear bars are visible at 2/32nds.

Tread Life

The life of a tyre before it is pulled from service; mileage.

Tread Rib

The tread section that runs around the circumference of the tyre separated by the tread grooves.

Tread Width

The width of a tyre’s tread.

Treadwear Indicator

Narrow bands, sometimes called wear bars, that appear across the tread of the tyre when only 2/32 inch of tread remains.

Tri Side-by-Side Compounding

A process that makes it possible to precisely place three different types of rubber compounds across the tread of a tyre.

Tyre

Also called pneumatic tyre, a precisely engineered assembly of rubber, chemicals, fabric, and metal, designed to provide traction, cushion road shock and carry a load under varying conditions.

Tyre Designation

An alphanumeric code molded into the sidewall of the tire that describes the tire’s size, including width, aspect ratio, rim diameter, load index, and speed rating. Most designations use the P-Metric system.

Tyre Mixing

A situation in which tyres of various brands, types, or sizes are mixed on a vehicle. This can lead to variations in the vehicle’s ride and handling characteristics.

Tyre Placard

A metal or paper tag permanently affixed to a vehicle, which indicates the appropriate tyre size and inflation pressures for the vehicle. The placard can ordinarily be found on either the driver’s doorpost, the glove box lid, or the fuel-filler door.