Prepare your semi to be Ready for the Road Ahead , with the Dual Dynamics 125 psi Cross Fire Dual Tire Pressure Equalization System that provides an equal distribution of tire pressure. To maintain equal pressure levels between dual tires, this replacement valve seamlessly mounts between dual tires to allow for a free flow of air between the two. Fashioned with robust materials to endure extreme pressure levels. FleetPride is your First Click in Heavy Duty .