PA6 - 2.7rv = Medium Viscosity Nylon
PA6 - 4.0rv = High Viscosity Nylon

Graph depicting %Increase in swelling of material when exposed to Water.

The amount of moisture absorbed by the material relates to the amount of swelling. In this test a 5mm specimen was submerged in water for various lengths of time and the moisture content then determined. As can be seen in the graph the higher viscosity nylon is more resistant to moisture absorption than the medium viscosity nylon. With wheels, the swelling due to moisture absorption can result in bore sizes reducing and wheels becoming tight on their axels leading to increased friction and rolling resistance and an increase in the rate of wear of the wheel.