In the manual chair the usual size of the rear wheel ranges from twenty to twenty-six inches in diameter. A larger wheel increases the height of the seat off the ground and decreases the rolling resistance, thus easing the effort of pushing. The rear wheels can be solid or pneumatic. Solid wheels have a low rolling resistance and are very easy to maintain. They are ideal for use in institutional settings or for indoor use in noncarpeted areas. Pneumatic wheels have better grip on carpeted surfaces and are better if there is going to be significant outdoor use, but they run the risk of flats and require higher maintenance. The flat tire problem can be circumvented by the use of a foam insert that can prevent leaks. Wire spokes are lighter in weight but higher in maintenance. Most older persons will select large plastic spokes referred to as mag wheels. The wheels can be offset posteriorly to decrease the risk of tipping backwards.
Hand rims are used to propel the chair. The materials used in hand rims vary from steel to aluminum, and the rims are often coated with rubber or plastic materials to assist grip and protect hands. Modifications to hand rims such as lugs (knobs) can be added to assist the person with a weak grip in pushing the wheelchair. Most wheelchairs are meant to be propelled with two hands, however, one-arm drive mechanisms are available. The front wheels are called the casters. These are usually eight inches in diameter, but like the rear wheels vary in size. These allow turning of the wheelchair. One needs to assure that the casters and footrests are properly positioned so as not to interfere with each other.