Toyota Yaris Sedan 2008 Quick Reference Manual page 161

2-5. Driving information
Trailer tongue load
n
The trailer cargo load should be distributed so that the tongue
load is 9 to 11% of the total trailer weight, not exceeding the
maximum 70 lb. (32 kg) (Tongue load / Total trailer weight × 100
= 9 to 11%)
The total trailer weight and tongue load can be measured with
platform scales found at a highway weighing station, building
supply company, trucking company, junk yard, etc.
146
Total trailer weight
Tongue load