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
HitchKnock sensor (3MZ-FE)
REPLACEMENT
1. DISCHARGE FUEL SYSTEM PRESSURE (See page 11-35 )
2. DRAIN ENGINE COOLANT (See page 16-26 )
3. REMOVE V-BANK COVER SUB-ASSY (See page 14-149 )
4. REMOVE AIR CLEANER CAP SUB-ASSY (See page 14-149 )
5. REMOVE EMISSION CONTROL VALVE SET (See page 14-149 )
6. REMOVE INTAKE AIR SURGE ...