Lexus 2004 GX470 Owner's Manual page 435

DRIVING TIPS
D The trailer cargo load should be distributed so that
the tongue load is 10% of the total trailer weight, not
exceeding the maximum of the following.
For weight carrying hitch 227 kg (500 lb.)
Also for weight distributing hitch 294 kg (650 lb.)
D Never load the trailer with more weight in the back
than in the front. About 60% of the trailer load should
be in the front half of the trailer and the remaining 40%
in the rear.
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