Tackling Tire Terminology

Tires are the only part of the car that keeps in contact with road, so what they do is vitally important. As with anything technical they have a fully loaded dictionary of lingo and terminology that can seem bizarre to the uninitiated. But knowing what some of the terms refer to is useful, particularly when buying new tires.

Here’s a handy guide to some of the most often used terms and what they mean.

• Air Pressure: Essentially it's the amount of air inside the tire. It's usually measured in pounds per square inch (psi), and it's dangerous to have it too low or too high.
• Balance: This is where a tire and a wheel spin with all their weight distributed evenly (hopefully).
• Bead: The inner edge of the tire, where it meets the wheel. It's reinforced with steel wires to prevent damage whenever a tire is moved on or off a wheel.
• Crown: This is the outer perimeter of the tyre. Load Index. The load capacity of a tire, that is the maximum weight it can support when properly inflated. It's usually measured in pounds.
• Friction: The physical force between the tire and the road that allows it to grip on to the surface.
• Hydroplaning: This is when tires lose contact with a wet surface, usually because they are worn or poorly treaded.
• Plus-sizing: A way to improve the look and performance of a vehicle. Involves altering the wheel diameter and the tire aspect ratio. Also referred to as "Inching up".
• Rotation: The changing of tires, say from front to rear, at regular intervals to maximize longevity of the tires.
• Sidewall: This is the area of the tire which is between the crown and the inner edges, where it is mounted on the rim of the wheel.
• Speed Rating: All tires are rated with a speed letter. The letters refer to the maximum speed a tire can withstand for a period of time without destroying itself. Some of the letters are P, Q, R, S, T, U, H, V, W, Y, Z. Each letter has a specific speed associated with it; from P which is 95 mph all the way up to Z which is 149+ mph
• Traction: The power to grip onto the road surface.
• Tread: The grooves, or depressions, which can be seen, or felt, on the crown. It's the part of the tire that comes into contact with the road.
• Treadwear Indicator: Also called 'wear bars'. These are narrow bands on the tire that appear when the tire is becoming worn down.

Hopefully now you'll be a little more 'tired', literally. Safe Driving.

Author Notes:

David Parker contributes and publishes news editorial to http://www.buying-tires.com.