Century EB-4 Owner's Manual page 21

Section I - SAFETY PRECAUTIONS (cont'd)
There are two key factors in safe towing:
1. Have enough front axle weight for safe steering.
2. Avoid excess rear axle weight.
The issue here is safety. Unsafe steering may cause a serious accident. It
is recommended that a safe steering formula that maintains at least 50
percent of the UNLADEN (unloaded) front axle weight, for towing, be used.
Unladen weights at front and rear axles.
The formula is expressed as follows: ML = .5FAW x WB/OH
where:
ML = maximum lifted load for safe steering.
FAW = unladen (unloaded) weight at front axle.
WB = wheel base or distance between the center of the front axle
to the center of the rear axle(s).
OH = overhang or distance from the center of the rear axle(s) to
the lift point of the towing device.
To use the formula, multiply the unladen weight at the front axle by .5.
Multiply the result by the wheel bases. Then, divide that result by the
overhang. So, you should calculate the maximum lifted load for each tow
truck, using this formula, post those limits in the truck and instruct each
driver to strictly observe those limits.
You should also observe gross vehicle weight ratings (GVWR), gross axle
weight ratings (GAWR), and the towing equipment ratings.
SAFE TOWING
I-17