I took the advice of the Heartland Manual and bought a torque wrench. The first 500 miles, I checked as the manual directed, and tightened lugnuts every time. Since then, I've been surprised that there are slightly loose lugnuts just about every time I check - at the start of every trip.
From the Heartland Manual:
Proper wheel nut torque is essential to safe and dependable trailering. The wheel and axle systems used
in RVs are similar in many ways to those used in cars and trucks, but they differ in several important ways. These
differences require special attention to wheel nut torque both while the trailer is new and throughout the trailer’s life.
Trailer wheels must carry much higher loads per wheel than passenger car or truck wheels. Furthermore, wheels
on tandem axle trailers do not steer, and are subjected to very high side load stress whenever the trailer makes a tight turn.
When you go around corners – especially slow, tight ones – the wheels on your trailer are subjected to these strong
side loads. This tends to flex the wheel and gradually loosen the wheel nuts. Although the materials and manufacturing
methods are maximized for this kind of service, these extra load stresses and flexing can cause loosening.
It is critical that the wheels be properly torque at the start of the trip and every 50 miles for the first 500 miles
of road operation. Although the wheels have been properly torqued before leaving the manufacturing plant, settling
and wearing in of components during the first few miles of operation may cause some loosening of the wheel nuts.
The wheel nut torque is 120 ft-lbs. Always use an accurate torque wrench to tighten wheel nuts. A torque wrench
with adequate accuracy is available at most automotive tool stores. Considering the overall investment in the trailer, this
is a very reasonable cost. Use of a torque wrench can also reduce the effort required to tighten the wheel nuts.
