For agricultural and recreational use, there are a wide variety of different tire sizes for all-terrain vehicles (ATVs). The process of choosing the correct ATV tire sizes can become very important depending on the intended use of the vehicle. The range of sizes include different widths, heights, and tread patterns so that an ATV user can select the right type of tire for the ground surface.
ATV tire sizes are identified utilizing a three-unit dimensioning system. This system differs slightly between metric and imperial measurements, but each type refers to the same three components, namely tire height, tire width, and wheel rim diameter. Using the imperial system of tire measurement, the dimensions are expressed in the format a x b – c, where a refers to the tire height, b the tire width, and c the wheel rim diameter, with all dimensions being given in inches.
When using the metric system of measurement, the tire labeling format differs slightly. In this system — and utilizing the same denominators as the imperial example above — the dimension are expressed as b / a x c. In this case, the tire width, b, is in millimeters, while the wheel rim diameter remains as a measurement in inches. Using the metric system of labeling ATV tire sizes, the denominator a actually refers to the tire sidewall depth, that is, the distance between the outer edge of the tire and the wheel rim. This sidewall depth is a percentage of the tire width and is referred to as the aspect ratio.
The ATV tire label 22 x 10 - 10 provides an example for demonstration. This tire has a height, or diameter, of 22 inches and a tire width of 10 inches and is designed to fit to a wheel rim 10 inches in diameter. This same tire in a metric format is 225/60 x 10. In this metric system, the tire sidewall depth is labeled as 60 as it is 60% of the tire width, 135 millimeters, or six inches.
Different ATV tire sizes work better for different applications. The majority of ATV tire sizes are suitable for more than one type of surface; general exceptions include those designed for sand or dune racing and tires specifically meant for street or tarmac use. Tarmac tires are similar in design to standard road-going vehicle tires, while sand tires are often wider with a tread pattern specially designed to dig into the soft surface. The majority of other tire sizes and tread styles are suitable for use in a range of surfaces from soft clay through to hard-packed stone tracks.