Issue link: http://read.dmtmag.com/i/34501
STATIC AND LOW SPEED LOAD AND PRESSURE COEFFICIENTS Do not exceed loads or air pressure limits of the wheel or rim 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 rim/wheel manufacturer for rim/wheel load and inflation capacities.) Load limits at various speeds for radial ply truck/bus tires used on improved surfaces. (1) 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) 71 thru 75 (1) 66 thru 70 (1) 51 thru 65 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 -12% -4% None +7% +9% +12% +17% +25% +45% +55% +75% +105% Pressure Change +5 psi +5 psi No increase 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) 1 thru 75 66 thru 70 51 thru 65 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 None None None +7% +9% +12% +17% +25% +45% +55% +75% +105% D. CONVENTIONAL TIRES Pressure Change No increase No increase No increase No increase No increase +10 psi +15 psi +20 psi +20 psi +20 psi 30 psi +30 psi Inflation Speed Range (mph) 71 thru 75 66 thru 70 51 thru 65 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 None None None +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: 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. 10 Section One: Tire Selection Pressure Change No increase No increase No increase No increase No increase +10 psi +15 psi +30 psi +30 psi +30 psi +40 psi +40 psi Inflation Inflation 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) 71 thru 75 (1) 66 thru 70 (1) 51 thru 65 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 -12% -4% None +9% +16% +24% +32% +60% +85% +115% +140% +185% Pressure Change +5 psi +5 psi No increase No increase No increase +10 psi +15 psi +30 psi +30 psi +30 psi +40 psi +40 psi Inflation