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Automotive Engineering other topics FAQ


Sample Load Calculation by tireman9
Posted: 22 Aug 05

Sample Load Calculation US Tire & Rim Association

NOTE THERE ARE A NUMBER OF ADDITIONAL REQUIREMENTS THAT MUST BE CONSIDERED BEFORE THE LOADS CALCULATED CAN BE APPLIED. Some of these are the max vehicle speed capability. Is the tire size new or is it already in the existing tables? Is the tire to be placed on a passenger vehicle or a multipurpose vehicel. Is the Max vehicle GVW Less than 10,000 lbs and not to be used for any new design after 1/1/05, among others. So please remember this is only a general guide to provide a partila view of the complexities involved.

For 50 series aspect ratio and above.


L = load in Kg     round to nearest Load Index value for tires approved after 7/85

K = 6.67*10**-5  ( 50 through 80 series )

P = Inflation pressure in kPa

Sd = (0.34848 + 0.6497(A))*S70 (mm)

S70 is section on a 70% width rim

A = Aspect Ratio   = H/S70

Dr = Rim Diameter in mm  (Rim Dia * 25.4 rounded to nearest whole mm )

To convert load to pounds:
         Convert rounded calculated load in full Kg to closest 1 pound

To convert Inflation to Psi
         Convert kPa to closest 1 psi for intermediate pressure and to next highest psi for the Maximum pressure. (35 psi for standard load tires)

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