An experimental method was developed for the measurement of air permeation leakage through tubeless automobile tires and wheels. A differential pressure measurement system was used with temperature as an independent parameter. The diffusion rates generally far exceeded the loss rates observed through either the valve core or the valve rim seal on several typical tires observed under normal static conditions.
While permeation loss rates vary from tire to tire, typical losses are of the order of 0.5 to 1.0 psi (3.4 to 6.9 kPa) per month at 70° F (21° C) ambient temperature. Losses increase rapidly with increase in temperature to about 1.5 psi (10.3 kPa) per month at 90°F (32°C).
An analytical model was developed which can predict pressure loss rates due to permeation under a variety of climatic conditions.