The BGR Contact Tire System is the first comprehensive flat proof tire system for many forms of transport. The BGR Tires website is offering a complete catalog of pinch and puncture proof wheel and tire solutions for the motorcycle market. the Contact Tire System is comprised of 3 elements. In the motorcycle version of the patented 2-chamber system, the outer chamber employs a soft puncture proof material that removes all "basketball bouncing" tendencies when striking obstacles and reduces wheel hop and deflection. The Outer Chamber of the BGR Tires 2-Chamber Tire System contains the Rock shield that provides protection from punctures and cushions the rider from tire deflection and hard impact when striking rocks, roots and other obstacles. The Rock Shield offers a hardness value similar to 5-8psi in conventional tires. (9) Rock Shield pieces fill the Outer Chamber of the wheel and are separated from the Inner Tube by the puncture-proof Tire Insert. The Tire Insert isolates the Outer Chamber from high pressure while protecting the Inner Chamber from pinch and puncture flats. The protected Inner Tube provides correct sidewall support and precise steering when inflated to 15-20psi. No rim locks are required above 14psi and no pinch flats are suffered. See all product descriptions for a better understanding of the complete Contact Tire System.