Don't think any car instruction manual would specifically mention towing,my car manual talks about heavy loading which a hitched caravan would impose on the car.
One of the manuals I download which is not for our region goes into quite a bit about maximum load limits but only for Australia. I did find some information on my V5 document concerning Mass in Service and Braked and Unbraked towiing limits.
For Australia...
CAUTION
While towing a trailer, check the engine coolant
temperature gauge regularly to prevent engine
overheating.
jA Tongue load
jB Total trailer load
jC Less than 10%
MAXIMUM LOAD LIMITS (for Australia)
Maximum trailer loads (including tyres and other
loaded equipment):
1) Never allow the total trailer load to exceed:
2) The total trailer load must be lower than the following
three values, even if it does not exceed
the maximum permissible trailer load:
• Towing capacity displayed on a tow-bar.
• Trailer’s gross vehicle mass marked on a
coupling body.
• Gross vehicle mass marked on a trailer data
plate.
The maximum trailer load that can be towed by your
vehicle depends on the towing equipment fitted to
the vehicle. Therefore, it is important to not only
have the correct equipment fitted, but also to use it
correctly. Towing loads greater than the value specified
for your vehicle or using towing equipment that
is not provided by NISSAN could seriously affect
the handling and/or performance of your vehicle.
Vehicle damage resulting from improper towing procedures
is not covered by NISSAN warranties. Information
on trailer towing and the required equipment
should be obtained from a NISSAN dealer or
qualified workshop.
Maximum rear gross axle weight
The rear gross axle weight must not exceed the
Gross Axle Weight Rating (GAWR).
Engine – Transmission Axle GAWR
R9M – CVT 2WD 1015 kg
MR20DD – 6MT 2WD 985 kg
MR20DD – CVT 2WD 1000 kg
The trailer must be loaded so that heavy goods are
placed over the axle.
Maximum tongue load
Never allow the tongue load to exceed 10% of the
total trailer load. If the tongue load exceeds 10%,
rearrange the cargo in the trailer.