Tire manufacturers engineer each model tire to handle specific needs, purposes, and environmental conditions. This specialization has led to the development of tire terminology that can be confusing to the uninitiated. Below are some common tire terms and explanations.
In commercial trucking, tire position refers to the axle on which the tires will be placed. The three main tire positions of a tractor-trailer are STEER, DRIVE, and TRAILER.
The STEER tire is mounted to the front axle of the tractor, and controls turning. Steer tires effect the ride and handling of the vehicle, and are typically designed with a ribbed tread design to channel water away for improved control. Many steer tires are considered “all position” tires, and can be used on any axle, though it may not be as efficient or cost-effective.
The DRIVE tire is mounted to the rear axle or axles of the tractor. Tire position here is further broken down to INSIDE and OUTSIDE, as drive tires are typically mounted in dual wheel configuration. Drive axles are powered by the transmission, thus giving forward thrust to the vehicle, so drive tires are usually designed with a siped or lug-type tread for superior traction on a variety of surfaces.
The TRAILER tire is mounted on any of the trailer axles. Again, tire position here may include both INSIDE and OUTSIDE tires, as many trailers utilize a dual wheel configuration. Trailer tires are designed to withstand heavy loads and brake forces, are optimized for free rolling, and typically have reinforced sidewalls to protect against damage caused by curbing.
Dual Wheel – An axle configuration where wheels and tires are installed in matched sets, two per side, for a total of four wheels per axle.
Siped – A tread design that includes slits cut across the rubber surface of a tire, to facilitate water dispersion and improve traction.
Lug-Type – A tread design characterized by a deep groove pattern, resulting in knobs, or “lugs” on the tire surface, which improve grip.
Curbing – Causing tires to rub against, or even climb onto, concrete curbs. This commonly occurs with rear or trailer tires, due to a wide turn radius and insufficient turn clearance.