The peak braking coefficient of tires has been measured on an over‐the‐road tire traction tester using a variety of active electronic filters. Filters are identified that produce an accurate peak braking coefficient measurement by visual chart interpretation or digital sampling methods.
This report presents comparative wet traction data on a sample of tires from locked wheel tests run by the Safety Research Laboratory of the National Highway Traffic Safety Administration in order to develop a data base for establishing traction standards. Identical tests were run on three surfaces at the Texas Transportation Institute and on two surfaces at the Uniform Tire Quality Grading Treadwear and Traction Test Facility, Goodfellow Air Force Base. The precision of these results demonstrates the feasibility of (1) using a two‐wheeled skid trailer for locked wheel tire traction grading and (2) constructing surfaces which will remain stable for the purpose of traction testing.
The mechanisms which cause shake on smooth roads and the procedures and equipment for removing it are reviewed. A critical comparison of various on‐ and off‐the‐car tire balancing methods is made. The effectiveness of tire grinding and trueing is reviewed with emphasis on the total system behavior. A statistical evaluation and analysis is presented of the potential errors contributed by off‐the‐car balancing and the vehicle itself, considering the imbalance vector components inherent in tire‐rim assemblies and vehicle axles. The use of a liquid tire balancer is also investigated.
This paper describes experiments and methodology employed in an attempt to develop a system for the grading of wet tire traction. Data from instrumented vehicle experiments and the University of Michigan Highway Safety Research Institute mobile tire tester are used to support the conclusions. The vehicle tests include J‐curve cornering and diagonal, locked‐wheel braking. The maneuvers are used to generate information on tire tractive properties and their dependence on tread depth, rim size, suspension, and surface conditions. Three tire force measures obtained with the mobile tire tester, the peak longitudinal, peak free‐rolling lateral, and locked‐wheel longitudinal coefficients of friction, are presented for a group of 90 percent of the original equipment tire sizes in use on American cars and are rank correlated with vehicle results. The results indicate the feasibility of defining minimum wet traction levels for various tire‐road interface properties.