Technical Paper
City Bus Tire Bead Heat Evaluation
1992-11-01
922457
Radial tires now approach 80% of the North American commercial tire business due to superior treadwear and fuel economy. One of the last areas for radial tire market penetration is the city bus market. A radial tire is less tolerant of high brake heat temperatures because: 1. There is less rubber and reinforcement bulk than a bias tire to act as an insulator in the bead area. 2. The steel ply is a good heat conductor. 3. High sulfur compounds are required for good wire adhesion and these compounds are susceptible to heat degradation. Radial tires are developed to withstand a maximum continuous running temperature of 90 degrees C. Exceeding this temperature for short periods causes no problem; however, longer exposure may cause a loss of material component strength. Therefore, it is important to know the heat flow characteristics between a brake drum and the tire. In this paper, various drum-bead heat studies will be discussed.