Toyota Sienna 2010 Owner's Manual page 228

2-5. Driving information
Trailer tongue load
■
The trailer cargo load should be distributed so that the tongue
load is 9 to 11% for weight carrying hitch or 15% for weight dis-
tributing hitch of the total trailer weight, not exceeding the maxi-
mum load of the following. (Tongue load / Total trailer weight x
100 = 9 to 11% or 15%)
Without towing package: 120 lb. (54 kg)
With towing package: 350 lb. (158 kg)
The total trailer weight and tongue load can be measured with
platform scales found at highway weighing stations, building
supply companies, trucking companies, junk yards, etc.
Towing a trailer
Contact your Toyota dealer for further information about additional
requirements such as a towing kit, etc.
230
Total trailer weight
Tongue load