The ergonomics of different tyres and tyre pressure during wheelchair propulsion.

It is believed that the newer solid tyres on wheelchairs perform as well as pneumatic tyres along with less cost and time for maintenance. The questions are: (1) do solid tyres perform as well as pneumatic tyres and (2) what is the critical level of pneumatic tyre pressure before wheeling efficiency decreases? Part one measured the rolling resistance differences of five commonly used wheelchair tyres (three pneumatic and two solid) under four different tyre pressures (100, 75, 50 and 25 of inflation). Part two measured the oxygen consumption in 15 participants with paraplegia, during wheelchair propulsion, comparing the same four levels of tyre inflation. The solid tyres performed worse than all three pneumatic tyres even when tyres were under-inflated to 25% of tyre pressure. Two of the pneumatic tyres showed significant decreases in rolling between 100 and 50%, but there were no significant differences in rolling distance between 100 and 75% pressure. The physiological study showed that energy expenditure increased significantly at 50% of tyre-inflation. Health care facilities are finding ways to decrease cost by using solid tyres on all wheelchairs. This study shows that benefits to clients and staff using pneumatic tyres far outweigh the minimal cost in time to maintain adequate tyre inflation.