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Appendix STATIC AND LOW SPEED LOAD AND PRESSURE COEFFICIENTS STATIC AND LOW SPEED LOAD AND PRESSURE COEFFICIENTS Do not exceed loads or pressure limits of the wheel without permission of the component manufacturer. Exceeding the legal speed limit is neither recommended nor endorsed. TRA (THE TIRE AND RIM ASSOCIATION, INC.) STANDARDS (These Tables apply to tires only. Consult wheel manufacturer for wheel load and inflation capacities.) Load limits at various speeds for radial ply truck-bus tires used on improved surfaces. A. METRIC AND WIDE BASE TIRES The service load and minimum (cold) inflation must comply with the following limitations unless a speed restriction is indicated on the tire.* Speed Range (mph) 41 thru 50 31 thru 40 21 thru 30 11 thru 20 6 thru 10 2.6 thru 5 Creep thru 2.5 Creep(2) Stationary % Load Change +7% +9% +12% +17% +25% +45% +55% +75% +105% Pressure Change No increase No increase +10 psi +15 psi +20 psi +20 psi +20 psi +30 psi +30 psi Note: For bias ply tires please consult the TRA Year Book. Load limits at various speeds for radial ply truck-bus tires, rated at 75 mph or above, used on improved surfaces. (1) C. METRIC AND WIDE BASE TIRES % Load Change Speed Range (mph) 41 thru 50 31 thru 40 21 thru 30 11 thru 20 6 thru 10 2.6 thru 5 Creep thru 2.5 Creep (2) Stationary +7% +9% +12% +17% +25% +45% +55% +75% +105% D. CONVENTIONAL TIRES Pressure Change No increase No increase +10 psi +15 psi +20 psi +20 psi +20 psi +30 psi +30 psi Inflation Speed Range (mph) 41 thru 50 31 thru 40 21 thru 30 11 thru 20 6 thru 10 (3) 2.6 thru 5 (3) Creep thru 2.5 (3) Creep (2)(3) Stationary (3) % Load Change +9% +16% +24% +32% +60% +85% +115% +140% +185% (1) These load and inflation changes are only required when exceeding the tire manufacturer's rated speed for the tire. (2) Apply these increases to Dual Loads and Inflation Pressures. (3) Creep – Motion for not over 200 feet in a 30-minute period. Note 1: Pressure Change No increase No increase +10 psi +15 psi +30 psi +30 psi +30 psi +40 psi +40 psi Inflation Inflation (1) B. CONVENTIONAL TIRES The service load and minimum (cold) inflation must comply with the following limitations unless a speed restriction is indicated on the tire.* Speed Range (mph) 41 thru 50 31 thru 40 21 thru 30 11 thru 20 6 thru 10 (2) 2.6 thru 5 (2) Creep thru 2.5 (2) Creep (2) (3) Stationary (2) % Load Change +9% +16% +24% +32% +60% +85% +115% +140% +185% Pressure Change No increase No increase +10 psi +15 psi +30 psi +30 psi +30 psi +40 psi +40 psi Inflation The inflation pressures shown in the referenced tables are minimum cold pressures for the various loads listed. Higher pressures should be used as follows: A. When required by the above speed/load table. B. When higher pressures are desirable to obtain improved operating performance. For speeds above 20 mph, the combined increases of A and B should not exceed 20 psi above the inflation specified for the maximum load of the tire. Note 2: Load limits at various speeds for: Tires used in highway service at restricted speed. Mining and logging tires used in intermittent highway service *Exceeding the legal speed limit is neither recommended or endorsed. 90