Tow Vehicle GARS vs GVWR
Good Evening; 1st off I've searched thru any & all threads I thought this might be in, but no such luck. Why is that the gross axle weight ratings on most tow vehicles, when added together, are grea...
Forum Discussion
Gross Axle Weight Rating is the rated load-carrying capacity of an individual axle and wheel assembly. (It represents the load that may be steadily sustained by the components in the system; i.e., tires, rims, hubs, bearing, axles, brakes, suspension, sub frame, etc. with the GAWR limited by the components with the lowest working rating".
And from RMA
• GAWR: Gross Axle Weight Rating (for each axle) -
The maximum weight rating that the components
(tires, rims/wheels, brakes, springs, and axle) of
each axle are designed to support. This is
determined by the lowest design capacity of any
component. In other words, if the wheels have the
lowest design capacity of any component on that
axle, installing tires with a higher load capacity
does not increase the GAWR. By regulation, the
tire load rating times the number of tires on that
axle must equal or exceed the GAWR for that axle.
My point here is brakes are a function of the GAWRs not GVWR. Same with our trailers.
Vehicle manufacturers may determine the GVWR of a vehicle by calculating the maximum load rating of the vehicles axles, tires, brakes, frame, suspension and wheels in order to come up with a GVWR rating. Also, a manufacturer may limit the GVWR if so desired. So they could have the componentry to rate higher but choose a lower rating at their discretion.
The F250/F350 SRW is a good example.
The F250 is rated at 10000 GVWR with 6100 RAWR.
The F350 SRW is the same truck specs and starts at 10000 GVWR but rates the same axle (higher rated wheels/tires and the rear spring pack) with a 6290 RAWR for more payload.
The higher rated 6730 RAWR and 7000 RAWR have the higher rated GVWRs up to 11500 for even more payload.
And from RMA
• GAWR: Gross Axle Weight Rating (for each axle) -
The maximum weight rating that the components
(tires, rims/wheels, brakes, springs, and axle) of
each axle are designed to support. This is
determined by the lowest design capacity of any
component. In other words, if the wheels have the
lowest design capacity of any component on that
axle, installing tires with a higher load capacity
does not increase the GAWR. By regulation, the
tire load rating times the number of tires on that
axle must equal or exceed the GAWR for that axle.
My point here is brakes are a function of the GAWRs not GVWR. Same with our trailers.
Vehicle manufacturers may determine the GVWR of a vehicle by calculating the maximum load rating of the vehicles axles, tires, brakes, frame, suspension and wheels in order to come up with a GVWR rating. Also, a manufacturer may limit the GVWR if so desired. So they could have the componentry to rate higher but choose a lower rating at their discretion.
The F250/F350 SRW is a good example.
The F250 is rated at 10000 GVWR with 6100 RAWR.
The F350 SRW is the same truck specs and starts at 10000 GVWR but rates the same axle (higher rated wheels/tires and the rear spring pack) with a 6290 RAWR for more payload.
The higher rated 6730 RAWR and 7000 RAWR have the higher rated GVWRs up to 11500 for even more payload.
