With a tandem
axle setup which does not share load perfectly (i.e. almost all of them...) changing the tongue height shifts load between the axles, and that's why pitch attitude would be particularly important to tandems, and not to single-axle trailers.
Even with a single axle, the weight
distribution between axle and hitch is changed by tilting the trailer. Since lifting the front up moves the mass of the trailer back closer to the axle, the hitch carries less load when tilted to a more nose-up attitude. When I first heard about this concern I thought it had to be a tiny effect, but it actually can be significant, and other members have posted their observations of measured hitch weights with different heights. Since many tow setups seemt to have stability problems with insufficient hitch weight
, towing more nose-up than intended could be a problem.
There could be bad aerodynamic
consequences of a nose-up attitude (perhaps lift causing lack of traction, like the rear of most cars at very high speeds), but personally I have not seen any factual analysis of this for trailers.
I tow my Boler level
- that is, the frame is horizontal when the whole rig is in the loaded condition - and took care to ensure that it would be that way.