Longacre Tireliefs are a pressure relief valve which are designed to screw into the wheels on competition cars (A 1/8" NPT tapped hole is required for fitment). They work by releasing tyre pressure build up as the tyre heats up during racing, keeping the tyre at the pressure which was set before the race. This keeps tyre grip more consistent throughout the race improving handling and grip.Prevents tyre pressure increasing as the tyre heats upConstant tyre pressure provides more consistent gripLightweight aluminium (just 9g so as not to effect wheel balance)3-40 Psi adjustment range (user settable)Mesh filter prevents debris from inside the tyre clogging the valveImportant - Please check with your race organiser if the use of Tireliefs is allowedNOTE: Tireliefs are designed ONLY to relieve normal tire pressure buildup on the track. They should not be used as a safety device.Sold as a set of 4