The large wheel of the wheelchair carries the main weight. There are several types of wheels with diameters of 51, 56, 61 and 66 cm. In addition to a few use environment requirements and the use of solid tires, pneumatic tires are often used. There are several types of small wheels with diameters of 12, 15, 18, and 20 cm. Small wheels with large diameters can easily cross small obstacles and special carpets.
However, the large diameter makes the space occupied by the entire wheelchair larger, making it inconvenient to move. The normal small wheel precedes the large wheel, but in wheelchairs for paraplegics of the lower limbs, the small wheel is often placed after the large wheel. It should be noted that the direction of the small wheel should be perpendicular to the large wheel during operation, otherwise it is easy to fall over.