Wheelchairindia casters come in a two variety of diameters and widths and each different style and size will have its own attributes that make it appropriate for different applications. The purpose of wheelchair casters is to stabilize the wheelchair while the drive wheels (powered wheels on a power wheelchair & large handrimmed wheels on a manual wheelchair) propel the wheelchair.
There are three types of wheelchair wheel for casters, air filled, solid and foam filled or flat free inserts. The tires on the casters can be a huge factor on how easily the wheelchair will roll over all terrain. Generally the harder the caster tire, the easier the wheelchair will roll and turn corners. The softer the caster tire, the harder it will be to propel the wheelchair and the harder it will be to turn the wheelchair.
Air wheel (Caster): are not terribly common but they will roll over soft terrain easier the solid tires. Although air tires are available on casters as small as 6" in diameter I never recommended them for tires less than 8" because the smaller the caster, the easier the tire goes soft and the harder it is to refill the air tire.
Solid wheel (Caster): are the best Caster wheel for those who want a wheelchair to roll and turn as easy as possible but they give the roughest ride over bumps and ridges in the ground surface. The biggest advantage is they are virtually maintenance free and they won't go flat and won't likely wear out in the life of the wheelchair.
Foam filled or flat free (Caster): inserts are basically air tires that have a semi-solid core. The advantage is they will stay harder than air tires and not be subject to flat tires but still give a bit softer ride than a solid tire. This type of caster tire will wear out over time and have to be replaced on wheelchairs that have heavy use and would be considered a compromise between air filled and solid caster tires.