What makes up a GVWR rating?
I am wondering what it is in the design of a trailer's frame and suspension or otherwise that gives it a particular GVWR rating. Is it the axles primarily? We have a trailer with a GVWR of 6800 lb...
Forum Discussion
Gil, there are many ways of establishing a trailer's GVWR.
Just from looking at manufacturer brochure numbers, is seems that some of the possibilities are:
GVWR = the sum of the ratings for each axle.
GVWR = the sum of the ratings for each axle plus an assumed addition for tongue weight.
GVWR = the sum of the load capacities for each tire.
GVWR = the sum of the load capacities for each tire plus an assumed addition for tongue weight.
GVWR = the maximum load which can be carried without exceeding the allowable stress at any point in the frame or suspension system.
In the first post, you mentioned having two 3500# axles. Based on the first two "methods", that should give you a GVWR of at least 7000#.
Have you looked at the DOT (assuming you have US-rated tires) "MAX LOAD" rating for the trailer tires? Multiplying that value by 4 would give another indication of possible GVWR.
Assuming each tire can carry more than 1700#, then it seems likely that KZ has performed a frame strength analysis and used that as the basis for establishing GVWR.
The KZ Spree Specifications Page shows 23 models -- all with 15" tires. There are nine GVWRs ranging from 6000# to 9500#. One model shows a GVWR of 7900# and three show 7950#.
If they really do have GVWRs which differ only by 50#, that does seem to increase the likelihood the GVWRs are based on frame strength.
But, that's just speculation on my part.
Ron
Just from looking at manufacturer brochure numbers, is seems that some of the possibilities are:
GVWR = the sum of the ratings for each axle.
GVWR = the sum of the ratings for each axle plus an assumed addition for tongue weight.
GVWR = the sum of the load capacities for each tire.
GVWR = the sum of the load capacities for each tire plus an assumed addition for tongue weight.
GVWR = the maximum load which can be carried without exceeding the allowable stress at any point in the frame or suspension system.
In the first post, you mentioned having two 3500# axles. Based on the first two "methods", that should give you a GVWR of at least 7000#.
Have you looked at the DOT (assuming you have US-rated tires) "MAX LOAD" rating for the trailer tires? Multiplying that value by 4 would give another indication of possible GVWR.
Assuming each tire can carry more than 1700#, then it seems likely that KZ has performed a frame strength analysis and used that as the basis for establishing GVWR.
The KZ Spree Specifications Page shows 23 models -- all with 15" tires. There are nine GVWRs ranging from 6000# to 9500#. One model shows a GVWR of 7900# and three show 7950#.
If they really do have GVWRs which differ only by 50#, that does seem to increase the likelihood the GVWRs are based on frame strength.
But, that's just speculation on my part.
Ron
