Maybe our motorhomes are getting a little heavy...

[dentmac]

The discrepancy can be due to the Drive:Tag ratio. Usually 60:40 (or 65:35 if you are trying to lighten the front end ) ( a BB trick ) As RV load increases, and one axle approaches max. GAWR the other axle is not at its maximum due to the ratio. The outcome is less load than the simple addition of the 2 axles GAWR.

May not be true , but sounds good Eh!