Tyres in English, or tires in American English, are ring-shaped parts, either pneumatic or solid, that fit around wheels to protect them and enhance their function. Pneumatic tyres are used on many types of vehicles, such as bicycles, motorcycles, cars, trucks, earthmovers, and aircrafts. A tyre enables and enhances better vehicle performance by providing traction and load support. A tyre (or tire) forms a flexible cushion between the vehicle and the road, which smooths out shock and makes for a more comfortable ride while keeping the wheel in more constant contact with the road.