The gross trailer weight should be distributed so that the tongue weight is 9% to 11%.
(Tongue weight /gross trailer weight x 100 = 9% to 11%)

If using a weight distributing hitch when towing, return the front axle to the same weight as before the trailer connection.
If front axle weight cannot be measured directly, measure the front fender height above the front axle before connection. Adjust weight distributing hitch torque until front fender is returned to the same height as before connection.
The gross trailer weight, gross axle weight and tongue weight can be measured with platform scales found at a highway weighing station, building supply company, trucking company, junk yard, etc.
Gcwr, twr and unbraked twr
HitchMaintenance
requirements
To ensure safe and economical driving, day-to-day care and regular
maintenance are essential. It is the owner’s responsibility to
perform regular checks. Toyota recommends the following maintenance:
General maintenance
General maintenance should be performed on a daily basis. This can
be done ...