Technical Dictionary

Air Pressure

The amount of air inside the tyre pressing outward on each square inch of tyre, which is expressed in pounds per square inch (psi) or kiloPascals (kPa), the metric designation for air pressure.

Airtight Synthetic Rubber

Formulated with virtually impermeable butyl rubber, this material replaces the inner tube in modern, tubeless tyres. Check you air pressure monthly, as some air loss occurs over time.

Alignment

When all wheels on the vehicle are adjusted so that they are pointed in the optimum direction relative to the road and each other.

All-season high-performance tyres

Tyres that deliver a measure of traction on snow and ice without sacrificing dry performance driving capabilities.

All-season traction

Indicates the tyre’s ability to provide a balance of traction in wet, dry, and winter conditions.

All-season tyres

Tyres that provide a good balance of traction in rain or snow with good tread life and a comfortable, quiet ride.

APS

An advanced silica-based winter rubber compound that helps provide flexibility where the tread surface makes contact with the road.

Aquaplaning

An extremely dangerous situation where water builds up in front of the tyres resulting in the tyres losing contact with the road surface. At this point, the vehicle is skimming on the water surface and is completely out of control. Also called hydroplaning.

Aramid

A synthetic fabric used in some tyres that is (pound-for-pound) stronger than steel.

Aspect Ratio

The relationship of a tyre’s sidewall height to its section width.

Asymmetrical Tread Design (AD)

Different tread patterns featured on either side of the tread that enhance and optimize performance for both wet and dry handling. The inside shoulder has more grooves for water evacuation and massive tread blocks on the outside shoulder make for maximum handling.