Wheels and tires

1. What is the most common type of wheelchair wheels? How do Mag wheels differ from spoke wheels?
2. What are the benefits of the posterior and anterior axle placement?
3. What are the advantages and disadvantages of solid rubber tires?
4. What are the advantages and disadvantages of pneumatic tires?
5. What is camber? How many degrees of camber maximizes lateral stability?
6. What are the advantages and disadvantages of increased camber?

Answers:
1. Mag wheels are most common, which are one piece and cast with metal alloy. They are maintenance free. Spoke wheels are lighter and easier to propel, but require more maintenance.
2. Posterior rear wheels give greater rolling resistance, more energy for propulsion, greater turning radius, and more stability (such as for loss of legs). Anterior rear wheels give less rolling resistance, less energy to propel, smaller turning radius, less stability, more maneuverability for possible "wheelies".
3. Solid rubber tires have a low rolling resistance on flat surfaces and there are no flat tires. However, they have less cushioning on bumpy surfaces and are heavy.
4. Pneumatic tires contain air and are lightweight for better ride on bumpy or carpeted surfaces but not as good on smooth surfaces.
5. Camber is the wheel angle with the vertical axis. 7 degrees maximizes lateral stability.
6. Higher camber makes the wheelchair easier to propel, increases stability, and tightens the turning radius. However, it increases the width of the chair, increases tire wear, and decreases seat height.