This is a brief followup to the just prior post, on the use of non-pneumatic (e.g., solid rubber) tires on wheelchairs.
I’m trying to work out what I should recommend if asked to replace more wheelchair tires. Traditional tires with air-filled inner tubes are much easier from the standpoint of the installer. The question is dealing with the drawbacks of those from the wheelchair user’s perspective.
The only way to guarantee that a wheelchair tire won’t go flat is to use a non-pneumatic tire. That includes solid rubber tires, and solid rubber inserts taking the place of an inner tube inside regular tires.
What I discovered in this post is that many anti-flat products available for bicyclists will not work for most wheelchairs, owing to the wheelchair’s use of narrow, high-pressure tires.
When all is said and done, between the past post and this post, I think I now have a fairly firm set of recommendations.
If you cannot tolerate a flat tire on-the-go, then opt for solid rubber tires (and not solid inserts in regular bike tires). But mount them using the $35 steel bolt-to-the-workbench device sold specifically for mounting such tires on wheelchair rims. Mounting them with simple hand tools is just too hard and too iffy.
If you can tolerate the occasional flat, the best option seems to be puncture-resistant tires and tubes. All the rest of the anti-flat products available for bicycle use — chemical sealants, anti-puncture tire liners, tire “wipers, and the like — either won’t work with typical wheelchair tires, or are not available off-the-shelf in the right size or configuration for that use.
Background
Solid rubber tires and solid rubber tire inserts definitely will not go flat. There’s no air in them in the first place.
But those tires have some drawbacks. Per the just-prior post, both of those non-pneumatic options are difficult to install using ordinary hand tools. In addition, solid inserts are difficult to purchase as they must match the tire fairly exactly.
Both types of non-pneumatic tires offer a harsher ride and higher rolling resistance than high-pressure pneumatic (air-filled) tires. And there are relatively few options available in the correct size for typical wheelchair rims.
By contrast, traditional pneumatic bike tires (tire plus inner tube) are easier to purchase and install, but they have two big drawbacks. They require frequent, routine re-inflation to maintain the correct pressure. Otherwise they go soft, and that raises rolling resistance. And they can go flat, unexpectedly, while you are out-and-about.
The latter is not just a problem for the high rolling resistance you get with a flat. It’s all too easy to roll a flat bike tire right off the rim, or to damage both the rim and the tire if you keep going on a flat tire.
This post is my research into minimizing the hassle from both of those drawbacks: routine periodic inflation, and flat tires.
Caveat 1: In the particular case I’m looking at, my options are 24″ x 1″ or 24″ x 1-3/8″ tires. This puts a lot of limits on the types of bike-tire solutions that can be adopted for wheelchair use. You might have other options available if your rims can accept wider tires.
Caveat 2: My only qualification for writing about this topic is that I’ve changed a lot of bike tires in my life. And I happen to be friends with someone who uses a manual wheelchair.
Routine inflation: An electric air pump can solve this problem.
Source: https://www.homedepot.com/p/Husky-120-Volt-Inflator-H120N/325096203
Best guess, $20 and a trip to Home Depot gives an adequate way to maintain tire air pressure up to 100 PSI.
I don’t think it’s worth belaboring this. All pneumatic bike tires lose air over time. It’s not a leak, per se. It’s that air diffuses through the rubber. (The same thing happens to rubber balloons and car tires, just much faster and much slower, respectively). The higher the tire pressure, and the thinner the tire/inner tube, the faster the tire goes soft. There’s no way to stop it that I have ever heard of.
This means that pneumatic tires have to be topped up on a routine basis. And in the modern world, the obvious solution for routine tire inflation is an electric air pump.
A standard full-sized manual bike tire pump doesn’t do the average wheelchair user much good for routine use. Not only are they designed to be used while standing up, they are designed to be fast, that is, to move a lot of air with each stroke. They do that by using a piston with a relatively large surface area. But wheelchair users often prefer high-pressure (e.g., 140 PSI) tires, for the low rolling resistance such tires provide. Even if a full-sized manual pump can achieve pressures like that, it takes a lot of force, owing to the large piston area.
The typical manual mini-bike-pump — the kind you take with you on a bike ride — is both slow and awkward to use. They are slow because they have tiny little pistons, suitable for pumping tires to high pressures using only your arm muscles. And they are awkward because they either clamp directly to the valve stem, or have just a short attaching hose, either of which essentially dictates exactly where the pump must be held, relative to the tire. In essence, those pumps are made for emergency on-the-road use. You can use them for routine tire maintenance, but I sure don’t.
Compressed C02 cartridge pumps are expensive for use in keeping tires routinely inflated. The poorly-designed ones appear hard to use, based on Amazon comments. But even for the well-designed ones, depending on the pump and the tire, you’d be spending $1.50 and tossing away a metal C02 cartridge every time you topped off your tires. Plus, based on what I read, C02-filled tires deflate more rapidly than air-filled tires, owing to something-something-something about the ability of C02 to diffuse through butyl rubber. You’d turn your routine tire maintenance into a $100-a-year habit, for no particular reason.
The efficient solution is an electric tire pump.
These days, you have your choice of 120 volt plug-in, 12 volt plug in, and rechargeable battery-operated pumps. You only have to check a few things:
- How loud are they?
- Can they do high pressures?
- How awkward are they to use?
- How long will they last in routine use?
- Is the battery replaceable?
And, of course, how much do they cost? Because, near as I can tell from reading Amazon comments, the cheaper pumps tend to fail several of the checks outlined above.
I have no specific recommendation to make, other than the Home Depot offering shown above. All I can suggest is (e.g.) reading the comments on pumps offered on Amazon. In particular, a lot of cheaper battery-operated pumps cannot produce high pressures despite what the Amazon listing might say. When in doubt, get one that plugs into the wall.
Avoiding flats: Nothing is bulletproof
If you absolutely, positively must not have a flat tire, the only real option is solid, non-pneumatic tires. In this section, I’m shooting for two things:
- A tire and tube setup that minimizes the risk of catastrophic flats.
- A simple, no-maintenance pump that can be kept on the wheelchair for emergency use as needed.
The pump is easy. Any C02-cartridge inflator that fits comfortably in the hand should be adequate, as would a standard bicycle mini-pump with the addition of an extension hose. Either would be small enough to be stored long-term on the wheelchair itself.
But finding a combination to minimize the chance of a wheelchair flat is hard, owing in part to the small size and high pressure of the typical wheelchair pneumatic tire. Puncture sealants (e.g., Slime (r)) do not appear to work at high pressure. Puncture proof tire liners do not appear to be available in the narrow widths required for wheelchair tires. The only options that work for typical wheelchair rims combine relatively expensive “puncture-resistant” tires with relatively expensive “thorn-resistant” inner tubes. Even with that, neither of those is likely to stand up to an ill-placed tack, nail, or screw.
So the bottom line is that there is no good anti-flat solution for pneumatic wheelchair tires. The best you can hope for is that any puncture is small enough that you can inflate the tire, on the go, enough to get you someplace where you can swap out the wheel.
Tire and tube setup.
An important restriction is that the only tires that I know will fit the rims I’ve been working with are 24″ x 1″, and 24″ x 1-3/8″ tires, designed for use with inner tubes. These are narrow by bicycle standards, and that limits choices quite a bit.
Puncture-resistant tire liner: No off-the-shelf option in this size.
Source: Amazon.com
These are (typically) just a tough piece of flexible plastic, designed to turn aside (e.g.) thorns. Note what the original Mr. Tuffy tire liners don’t say: Nails, tacks, screws, staples, and similar. Given that I’ve had nails go right through the tread of a steel-belted radial car tire, I’m pretty sure a piece of plastic isn’t going to stop them in a bike tire.
But it’s moot anyway. Near as I can tell, all the ones made for bicycles are too large for 1-3/8″ tires, and are certainly too large for 1″ tires. For the Mr. Tuffy brand, 24″ wheel sizing starts at 1.95″ and goes up from there.
At best, I could cut them down and use them. But I’d have to sand down the edges to be sure that the tire liners themselves didn’t cut the tube.
Tire sealants: Dubious in higher-pressure tires.
Slime (r) does not make ready-made self-sealing inner tubes sized for a 1-3/8 tire. That said, the original Slime (r) sealant was sold in bottles, to be squeezed into a bike inner tube after removing the valve core. So it’s easy enough to make self-sealing 1″ or 1-3/8″ tubes from standard tubes and a bottle of Slime (r). By reputation, this will stop (or greatly slow) leaks from small punctures for about two years. After which, I think you have to remove and replace the old tubes.
So that’s an option. Based on what I read on the internet, Slime works, somewhat. Won’t stop a rip or tear in the tire. May not seal fully. But gives you enough sealant to get home on a tire with a small puncture.
This seemingly-knowledgeable user provides a major caveat:
Tire pressures above 45 psi are less effective at sealing, and above 60 psi, don’t expect any effectiveness at all.
Oddly, Slime (r) itself does not mention this limitation. But now that I Google Slime (r) and tire pressure, I see warnings in multiple locations that Slime (r) and similar sealants will not work well in high-pressure tube tires. I’m not entirely sure how accurate that is, but until proven otherwise, that’s a caveat for tires in the 100 to 140 PSI range.
FWIW, a competing product in this segment — Flat Out — specifically says “fat tire bikes” (reference). The implication there is that this sealant would not work in (e.g.) road bikes with high-pressure tires.
Beyond that, Slime has a reputation for sometimes causing problems such as blocked valve stems. All things considered, Slime (r) may be reasonable for low-pressure (“fat”) bike tires, but whether or not it will work well and without issues for thin, high-pressure wheelchair tires is an open question.
A final issue is the use of Slime (r) in mounted tires that might be stored, unused, for a considerable length of time. Rumor has it that Slime (r) can “pile up” in the low section of the tire. If you’re getting close to the point where the Slime loses its ability to flow, you may end up picking up a replacement wheelchair tire only to find that the low section of the tire (as stored) is now solidified Slime.
Puncture-resistant tire: Expensive and somewhat effective.
As with tire liners, these aren’t a bulletproof solution. It’s puncture-resistant, not puncture proof. Near as I can tell, the only puncture-resistant tire marketed in the 24″ x 1-3/8″ size in the U.S. is marketed as a wheelchair tire. Hence it costs two or three times as much as a regular tire.
Puncture-resistant tube: Expensive, effectiveness unknown.
There are a handful of “thorn-resistant” (that is, extra-thick) inner tubes marketed in the 24″ x 1-3/8″ size. These appear to cost about two to four times as much as a regular inner tube. As with puncture-resistant tires, these are unlikely to stop a tack, nail, or screw. Whether they provide any additional resistance to punctures from man-made objects, I don’t know.
Run flat tire: No option in this size.
There are now foam inserts for bike tires that provide some degree of run-flat capability. These are oriented toward tubeless tires typically used by (e.g.) bike racers. Near as I can tell, there is no run-flat tire option available for something as small as 24″ x 1-3/8.
Tire wipers: Maybe, but requires D-I-Y mounting.
A final offering for minimizing punctures goes by various names, but probably “tire wipers” is sufficiently descriptive. These are typically wires that ride lightly on the tire, and knock off any solid debris that has stuck to the tire, including tacks, nails, and thorns. The idea is that it typically takes several tire revolutions for such debris to penetrate the tire, and if you can knock it away, it won’t puncture the tire. These typically mount (e.g.) the same place as the brake calipers on a bike, which means that you’d have to device a custom mounting for use in a wheelchair.
Emergency pump: C02 inflator or Standard bike mini-pump plus long adapter hose.
Based on what I read on the internet, plenty of wheelchair users adopt standard bike mini-pumps for tire inflation. These pumps are capable of reaching the (e.g.) 140 PSI required for high-pressure tires, but tend to be slow to inflate a tire, because of that.
The main drawback that I see, for on-the-go use, is that most of these pumps require direct attachment to the valve stem. That means that the user would have to hold the pump to the side, stabilize it on the wheel, and pump up the tire in that awkward position.
I think it’s far easier just to add a two-foot air hose, readily available from Amazon. That would allow a person seated in a wheelchair to inflate the wheel by holding the pump comfortably in the lap, rather than leaning over to manipulate a pump directly attached to a valve stem.
But by far the most obvious solution is a C02 inflator. These are compact enough to be held in one hand, and so should be readily usable by a seated wheelchair user to inflate a low tire on-the-go. A single small (16 gram) C02 cartridge should be adequate to bring a 24″ x 1-3/8 tire up to a reasonable working pressure.
A battery-operated rechargeable tire pump is a distant runner-up. Most of these are relatively bulky. Many of the less expensive ones cannot generate high pressures. And even with that, the batteries would slowly self-discharge, meaning that the user would have to remember to charge the pump periodically. That’s just begging to find that the battery is dead, just when you need it the most.
Conclusion
For pneumatic wheelchair tires, periodic maintenance of tire pressure isn’t much of an issue. Reliable plug-in electric inflator pumps capable of 100 PSI are readily available. These can be had with reasonably long air hoses, allowing the user considerable leeway in hooking the pump up to the valve stem. All that is required is remembering to use it on a regular basis.
The big problem is flat tires while out-and-about. There, many of the off-the-shelf solutions available to bicyclists — in-tire sealants, puncture-resistant liners, run-flat tires, and “tire wipers” — are not available (off-the-shelf) for narrow, high-pressure pneumatic tires typically used on wheelchairs.
That only leaves puncture-resistant tires and tubes. Those may slow down the rate at which flats occur, but neither of those will stop sharp metal objects such as tacks, nails, or screws.
I guess my bottom line is this. If you can tolerate the occasional flat tire, then go with high-end “puncture resistant” tires and tubes. Forget Slime (r), tire liners, tire wipers, and similar makeshift solutions. If not, I’d go with solid-rubber tires (not inserts), along with the steel bench-mounted tool used to install those tires safely on wheel rims.
