Presentation on theme: "Why Do Tires Lose Air? Permeation – Rubber is not 100% impermeable –The pressurized air inside the tire is seeking equilibrium with the atmospheric pressure."— Presentation transcript:
Why Do Tires Lose Air? Permeation – Rubber is not 100% impermeable –The pressurized air inside the tire is seeking equilibrium with the atmospheric pressure outside the tire. –Oxygen molecules migrate through the tire’s sidewalls and belts/tread area (about 75% of air loss), around the tire bead (about 15%) and through or around the valve stem (about 10%) according to Bridgestone/Firestone (source: Tire Business 9/22/03).
Features: Nitrogen permeates a tire at a rate 3 to 4 times slower than oxygen resulting in a slower rate of pressure loss. Nitrogen is an inert non-flammable gas. Nitrogen is a dry gas because of its inert qualities which all but eliminate oxidation. Nitrogen in Tires
Benefits: More consistent inflation pressure. Improved tread life. Potential for better fuel mileage. Cooler running tires. Decreased oxidation. Nitrogen in Tires
Reduced pressure build up: maintaining pressure reduces the deflection, which again prevents heat build-up and reduces the chance of separation Over-pressurization is as problematic as under-pressurization Increased tire pressure above the recommended inflation point can reduce the contact patch and thus reduce the maximum possible grip levels. Reduced moisture content introduced to the tire Nitrogen is dry because of it’s inert qualities. Many of the causes of failure in a tire can be attributed to moist air being introduced internally to the tire. Moisture causes rusting, especially of the valve stem, increasing leakage. Heating in tires is often caused by vaporization of the moisture.
Separation by Permeation Hollow Fibre H2OH2OCO 2 O2O2 Ar Air Nitrogen Air Oxygen Nitrogen