Tire tread is the lined or blocked pattern on the surface of a tire that provides traction for the tire. Often referred to as a caterpillar track, tread is found on the tire of any automobile. The tread pattern differs with different tires and different automobiles, but the use is the same.
Found on the surfaces of the wheel that come in contact with the ground, tire tread is often patterned in lines or blocks, and can be up to many inches or centimeters deep. The tread allows rain, snow, mud, or any other element to pass through the tire without the automobile losing traction.
The treads are cut deep to allow substances to pass through them without interfering with the motion of the wheels, and then pass back out. They are essential in preventing hydroplaning and from keeping some automobiles from getting stuck in snow or mud. Some tires, known as slicks, are made with little or no tread, and are used strictly for racing on dry surfaces.
Regular street tires on standard vehicles are equipped with similar treads from car to car, and tire to tire. These are to combat the everyday elements of rain or snow. Other tire treads, like those found on mud tires or all terrain vehicles, are much deeper and spaced much further apart. These specialized treads allow for ease of movement through thick mud and off-road conditions. The knob patterns of these treads allow the tire to dig into the mud and expel it without sticking.
Though not always used off-road, motorcycles and mountain bikes are equipped with tire tread similar to that of a truck or all terrain vehicle. This increased treading capability is used to provide better traction for a much lighter vehicle more susceptible to losing stability. The smaller surface area provided on these larger-tread tires causes the tread to wear down more quickly.
Through miles of driving, tire tread will decrease as the surface area wears off through too much contact with the road. With less surface area, the treads became shallower, allowing them to provide less traction. One simple way of determining when to change or retread your tires is when the tread reaches a height of less than a penny. At this point, new tires can be installed on the car, or the old tires can be improved through a process called retreading.
Many military or heavy-duty vehicles feature metal track segments within their tires. These reinforced treads allow for extra movement for a vehicle too heavy to benefit from a normal sized or rubber tire tread.