Gross axle weight rating


The gross axle weight rating is the maximum distributed weight that may be supported by an axle of a road vehicle. Typically, GAWR is followed by either the letters FR or RR, which indicate front or rear axles respectively.

Importance

Road damage rises steeply with axle weight, and is estimated "as a rule of thumb... for reasonably strong pavement surfaces" to be proportional to the fourth power of the axle weight. This means that doubling the axle weight will increase road damage =16 times. For this reason trucks with a high axle weight are heavily taxed in most countries.
Examples of GAWR on common axles.
AxleGAWR Manufacturer
Dana 302,770 lbsDana Holding Corporation
Dana 352,770 lbsDana Holding Corporation
Dana 443,500 lbsDana Holding Corporation
Dana 505,000 lbsDana Holding Corporation
Dana 606,500 lbsDana Holding Corporation
Dana S 607,000 lbsDana Holding Corporation
Dana 7010,000 lbsDana Holding Corporation
Dana 8012,000 lbsDana Holding Corporation
Dana S 11014,706 lbsDana Holding Corporation
Dana S 13016,000 lbsDana Holding Corporation
Ford 9-inch axle3,600 lbsFord Motor Company
Ford 8.8 axle3,800 lbsVisteon
Sterling 10.5 axle9,750 lbsVisteon
10.5" Corporate 14 Bolt Differential8,600 lbsAmerican Axle
11.5 AAM10,000 lbsAmerican Axle
10.5 AAM9,000 lbsAmerican Axle
Saginaw 9.5-inch axle6,000 lbsAmerican Axle

Maximum weight laws

In the EU and U.S. legal maximum load restrictions are placed on weight, independent of manufacturer's rating. In the EU a tractor can generally have on a single axle, with suspension type and number of tires often allowing slightly higher loads. In the U.S. weight restrictions are generally on a single axle, and on a tandem. The primary factor is distance between axle centerlines, also used to measure bridge formulas. A bridge formula does not reduce axle load allowance, rather gross vehicle weight, which can affect load distribution and actual axle weights.