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%)

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
HitchStandard bolt
HOW TO DETERMINE BOLT STRENGTH
SPECIFIED TORQUE FOR STANDARD BOLTS
HOW TO DETERMINE NUT STRENGTH
HINT:
*: Nut with 1 or more marks on one side surface of the nut.
Use a nut with the same nut strength classification number
(or greater) as the bolt strength classification number ...
On-vehicle inspection
NOTICE:
In this section, the terms "cold" and "hot" refer to the
temperature of the coils. "Cold" means approximately -
10°C (14°F) to 50°C (122°F). "Hot" means approximately
50°C (122°F) to 100°C (212°F).
1. INSPECT IGNITION C ...
Installing the spare tire
Remove any dirt or foreign matter
from the wheel contact surface.
If foreign matter is on the wheel
contact surface, the wheel nuts
may loosen while the vehicle is in
motion, causing the tire to come
off.
Install the tire and loosely
tighten each wheel nut by hand
by ...