Tires and belts are subject to significant increases in temperature due to heat build-up in the various rubber construction components during rolling. Automotive hoses typically carry liquids at high temperatures. This can lead to a decrease in structural integrity and occasionally, to catastrophic failures. This condition is exacerbated, in the case of tires, by under-inflation and/or overloading, and/or high speeds, such that flexing frequencies and amplitudes are increased. Tire pressure indicators, which are being incorporated into the display systems for some motor vehicles, generally require sophisticated technology and relatively high expense. However, tire pressure indicators do not measure the effect of low tire pressure, i.e., a temperature increase. Elevated tire temperature can be a more direct indication of problems with tire maintenance, including, but not limited to, under-inflation. Proper tire inflation is known to have a significant impact on fuel consumption as well.
Heat generation in tires is related to the energy loss per deformation cycle, and is proportional to the first power of the frequency and to the second power of the amplitude (energy loss∝frequency+amplitude2) in the dynamic response of rubbers. Because rubber is a very poor conductor of heat, the temperature increase is a coupled, sensitive indicator of poor tire maintenance and abuse.
Heretofore, temperatures have been difficult to monitor in rubber products, such as tires, belts, and vibration isolation components. A need exists for a tire safety indicator which is capable of warning drivers and observers of impending tire failures due to overheating, from under-inflation or other causes. Likewise, a need also exists for an indicator which is capable of warning an observer of impending failure of other rubber products due to overheating.