BMX wheels are usually 20 inches in diameter, much smaller than mountain bike or road bike wheels. Smaller wheels make the bike more agile and responsive, ideal for tricks and jump. However, some BMX riders prefer larger wheels, such as 22 or 24 inches, for more stability and speed on dirt tracks or trails.
BMX wheels are made of different materials depending on their purpose and durability. The most common materials are steel, aluminium and carbon fibre. Steel wheels are heavy but strong and cheap, while aluminium wheels are lighter but more expensive and prone to denting. Carbon fibre wheels are light and stiff but costly and can shatter or crack if impacted severely.
Another important component of BMX wheels is the hub, which connects the wheel to the axle and allows it to spin freely. BMX hubs can be either freewheel or cassette type. Freewheel hubs have a ratchet mechanism that allows the wheel to coast when not pedalling, while cassette hubs have a fixed cog that makes the wheel spin with the pedals at all times. Freewheel hubs are easier to maintain but less reliable than cassette hubs.
BMX tyres are also different from other bike tyres in terms of size, tread pattern and pressure. BMX tyres are usually wider than other bike tyres, ranging from 1.75 to 2.5 inches in width. Wider tyres provide more grip and cushioning on rough surfaces and add weight and rolling resistance. BMX tyres also have various tread patterns depending on the terrain they are designed for. For example, smooth tyres are good for street riding, knobby tyres for dirt riding, and semi-slick tyres for park riding.
BMX tyre pressure is also a matter of personal preference and riding style. Some riders like to run their tyres at low pressure (around 40 psi) for more traction and shock absorption, while others like running them at high pressure (around 80 psi) for less rolling resistance and better control.