What You Should Know About Wheelchair Tires

What You Should Know About Wheelchair Tires

Getting you from point-A to point-B in a wheelchair is more than just a wheel issue, per se. The wheel accessories you choose will be determined by how and where you use the chair. Normally, wheelchairs have two sets of wheels – two large ones in the back and two smaller ones in the front. However, there are some everyday and specialized sports (e.g., tennis, basketball, etc.) wheelchairs that have only one small wheel in the front. (Some power wheelchairs have three sets of wheels; six, altogether.)

Wheels are made up of various components: tires, rims, push-rims, spokes or Mag-wheels (magnesium, solid), small or large button “quick-release axles” and front-wheel casters. (Quick-release axles are for changing different-size wheels on the same axle in a sports-related environ-ment.) The tire is still the only part of the wheel that makes ground contact. Some manual chair- users have several sets of tires for seasonal or climate changes. The rear wheels are the largest on the manual chairs that aid in “self-propelling". They are referred to as the "drive-wheels" because of the “push-rims” attached to the rims of the tires. Chairs designed for a caregiver or attendant to push may have larger tires in the front since there is no need for "drive-wheels".

There are several factors to consider when choosing the most suitable wheel-and-tire configur-ation. Many frames cannot be modified to accept all the sizes of wheels and tires. Therefore, it is advisable to save the wheelchair's serial number and tire-details in the case of a replacement- situation along with the seat-width, depth, frame-color and other pertinent factory information that may be needed at a later time in the life of the wheelchair. 

Tires are known to go flat. There are two classes of tires - pneumatic (air) and puncture-proof (solid and “flat-free”). How you use and where you ride will help to decide which equipment is best for you. High-pressure tires are narrower than the everyday pneumatic tire. The tread pattern is minimal - not as deep as a pneumatic tire while requiring a greater inflation pressure. Many manufacturers recommend tires that are designed with increased camber and tread to be “off-center” to maintain good surface contact. The tire is of a smooth, light-tread for indoors and thin for mobility. For outdoors and better traction, the tire is wider with a medium, knobby tread.

Pneumatic Tires

They are made of rubber and require an inner-tube, under pressure. If you want greater perform-ance, a combination tube-and-tire is preferred or a Kevlar tire (used to make bulletproof vests) with a high-pressure inner-tube (180 psi). Pneumatic tires are widely used on most manual and power wheelchairs because they are generally lighter, shock-absorbing and offer good traction on most terrains.

While pneumatic tires are the most popular, they require the highest degree of maintenance. This is because the inserts consist of a thin liner that can be easily punctured by thorns, nails or other sharp objects penetrating through the tire. With these tires, you must always be prepared for a flat, especially if you spend a lot of time outdoors. You can learn to change your own tire, find a local bike-shop, use an attendant or use a friend familiar with bike and/or wheelchair mainten-ance. In addition, you must keep a close eye on maintaining the appropriate pressure level since leaks from pneumatic tires are common and, thus, should be replaced every couple of months.

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Puncture-Proof Tires

These are made of rubber or plastic (usually polyurethane). The rubber puncture-proof tires are similar to the pneumatics but the inner-tube consists of a solid material such as foam, plastic or rubber. These tires are essentially “flat-free” and require less maintenance than the pneumatics. However, a single, solid insert is generally heavier by an average of 1.5 times that of a single pneumatic insert. The combined difference in weight between having two pneumatic inserts and two solid inserts is approximately two to four pounds, depending on the material. While this does not sound like much, the additional weight can have a significant impact when it comes to transporting and/or propelling the wheelchair. They are also stiffer, not as shock-absorbing and tend not to grip the surface as well. These features may adversely affect the performance of your chair if you spend time outdoors in slippery conditions, if you often travel up-and-down hills or if you ride often on rough and/or rocky surfaces.

Replacing a solid insert can be very difficult to do on your own and should be taken to an expert, authorized service center. Unfortunately, servicing a wheel can be expensive. Changing a tire with a solid insert takes a little longer than a pneumatic insert so you can expect the cost for the service to be higher, as well. Bicycle shops can also provide repair or installation services on most wheelchair wheels and tires and are, generally, more economical. 

Also, there are puncture-proof tires that consist of solid plastic (no inserts). These tires are, generally, the least expensive but are also low performance, greatly reducing your comfort and can become damaged rather easily. Solid plastic tires are commonly found on hospital chairs that are designed for indoor use, only. New technologies have enabled puncture-proof tires to become more lightweight and comfortable user while still providing longer wear. Typically, these tires are constructed of a semi-pneumatic foam and/or rubber combination and come in various tread-designs and sizes.

Pneumatic tires and tubes are the most inexpensive combination to buy. For a standard, rear tire for manual wheelchairs, prices range from $10 to $45 per tire, depending on the materials used. They are made of a lower grade rubber with simple wire reinforcing beads that hold the tire inside the rim edges. The more expensive tires are made out of a higher quality rubber since the reinforcing on the sidewalls and bead are made from Kevlar. In general, puncture-proof inserts made of foam are more expensive than those made of a hard, plastic-type material.  

Tires are available in many different tread designs and widths, accommodating almost any type of terrain, as well as mobility requirements. Treads range from very smooth to extremely knobby such as those typically seen on high performance mountain bikes. The smoother the tread and the thinner the tire, the less rolling resistance required to push the wheelchair. If a majority of time is spent indoors, a smooth to lightly treaded, thin tire is desirable. If a lot of time is spent outdoors, a wider tire with a medium knobby tread has better traction on rough surfaces. Special tread designs and widths are available for traversing over snow, dirt, turf and grass, as well.

Power wheelchair users tend to use medium treads and thicker tires on all wheels to accommo-date many different surfaces with smooth treads not being a problem with a power-chair. Many manual chairs are not equipped to support different wheel sizes. The most appropriate diameter is determined by how long your arms are and how high or low you sit in your chair. You should be able to easily reach the entire, upper half of the push-rim without bending forward, without hunching your shoulders and without flexing your elbow out too far.

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Pneumatic vs. Puncture-Proof

                                           PROS                                                           CONS                                         ====================================================================

                         ● More light-weigh                          ● High maintenance

                         ● More shock-absorbing                  ● Air-insert thin liner that can be easily                

                         ● Good traction on most terrain          punctured by sharp object             Pneumatic                                                                ● Maintain PSI since air tends to leak over

                                                                                      time

                                                                                  ● Inner air tubes should be replaced every 3-4

                                                                                     months depending on usage to reduce

                                                                                     potential for flats due to wear

                                                                                  ● Replace outer tire 6-9 months when tread

                                                                                     appears worn or cracked.

====================================================================

                                 ● Essentially flat-free                        ● Heavier

Puncture-Proof      ● Requires less maintenance (the      ● Less shock-absorbing

same pair of solid inserts can be    ● Replacement can be costly and

used over and over again)                  difficult

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Casters

The front tires on a wheelchair are generally referred to as “casters” and are necessary for steering and maneuvering the wheelchair. Smaller casters provide for greater foot clearance and agility but are more apt to be caught in grooves and depressions or cause forward falls. They are often found on high performance, ultra-light and sports wheelchairs. The larger casters can provide more security since they ride over different surfaces more easily. Like rear tires, casters can be either pneumatic or solid, usually made of polyurethane, are durable but do not offer as much comfort as the pneumatics. NOTE: “Frog-Leg-Suspension” casters place a polymer shock-absorber at the point where most vibration occurs.

OVERALL

PROS

• The high-pressure tire is narrower than an everyday tire that decreases contact area with the floor (smaller footprint). The treads are fewer and shallower which decreases rolling-resistance. This results in the chair becoming easier to push and rolls further per push.
• High-pressure tires are commonly lighter than the standard pneumatics.
• Many users prefer to trade-off the softer ride of a conventional pneumatic for the improved push-ability of this type of tire.
• Favored by athletes for performance reasons.
• Have a “protection-belt” made from natural rubber.
• Skid-Free.
• Can handle a large amount of broken glass.

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CONS

• The small volume of air at higher pressure does not afford as much shock absorption, thus it makes for a harder ride than a conventional pneumatic tire.
• The smaller “footprint” of the tire may also result in diminished traction on wet or slippery surfaces.
• Smaller, shallower treads tend to wear out quicker than a conventional pneumatic when used for street use.
• May require a valve converter for inflation of the tires.

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