Area 42

To not leak is devine!

My homemade all-terrain power wheelchair/scooter has made a few more trips via Austin’s Capitol Metro system. Rolling to and from bus stops, I can hardly avoid the patches of broken glass and other debris that gather along the roadside. What if a tire goes flat?

For that matter, why use pneumatic tires in the first place? Edmond Wheelchair Repair and Supply carries non-marking tires in the size I wanted in both pneumatic and foam-filled “flat-free” models. I prefer hard tires, and you can’t adjust the foam-filled tires’ ride. I also admit it matters that the flat-free tires cost twice as much.

Given my choice of pneumatic tires, I had several options for flat control:

• Carry a pump and patch kit.
• Carry a CO2 inflator and patch kit.
• Carry a “fix-a-flat” type inflator (if I can find one for for this style of tire).
• Install “self-repairing” tire sealant in the tires.

I do intend to carry a patch kit and pump, but the idea of executing a roadside tire repair is scary. I am mobility impaired.

I best like the idea of having my tires self-repair any punctures that occur, if possible. I’ve found two similar “self-repairing” tire sealants. The one I see around most is Slime. A similar product, AmerSeal, isn’t as prominent on the web, but it seems to be well established in commercial and industrial markets.

Slime and AmerSeal both work the same way. The sealant is a mixture of liquid and suspended solids that you install through the tire’s valve stem. When a leak occurs, pressure and motion force some sealant into the leak, where the suspended solids pack together to plug the hole.

There are a few differences between Slime and AmerSeal that seem significant:

• Slime is claimed to be non-toxic. AmerSeal is harmful if swallowed (contains ethylene glycol).
• Slime has different formulas for tubed and tubeless tires. AmerSeal is claimed to work in both. Both brands claim to work better in tubeless tires than in tubed ones, though.
• Slime recommends replacement two years after installation. AmerSeal is claimed to last indefinitely.
• Slime seems to be marketed as a roadside repair solution. AmerSeal is sold as preventive maintenance.
• Slime is bright green. AmerSeal is off-white.

The color was actually a deciding factor for me. I read that Slime might ooze for a while after the tire is punctured, leaving bright green dots on the floor. Both brands claim easy clean-up, but I decided a trail of off-white dots might attract less attention in the workplace. 

Both products install through a Schrader type valve with the valve core removed. Both products include a short hose and the required valve tool. AmerSeal’s tool is a nice metal valve cap/tool combo. Neither brand supports installation in Presta-valve tubes, although Slime sells pre-Slimed tubes with Presta-type valves. 

The instructions are similar and fairly clear for both products. The valve tool turns left (counter clockwise) to loosen. My tires’ valve cores were very snug and required a firm twist. If the tire is full, let some pressure bleed off before unscrewing the core completely. Don’t lose it!

As you “pump” in the sealant, release between squeezes to let the bottle backfill with air from the tire. If you’re installing less than a whole bottle, be wary of the AmerSeal label’s “1-oz” graduations. In my specimen, these omitted zero and were scaled a little smaller than one ounce per mark. I guessed the actual midpoint to be around mark 9 or 10 on my 16-oz bottles, but this might vary for different printings.

For my wheelchair tires, AmerSeal’s chart recommended 16 oz. in each of the big 16-inch tires (size 4.00-8) and 8 oz. in each of the 8-inch dolly wheels (size 2.00-4). That’s a lot of stuff, roughly twice what Slime recommends for their product, and I think AmerSeal is more expensive. Still, if it does what it’s supposed to and it really lasts the lifetime of the tire, that’s a pretty cheap investment. I’ve spent lots more for much less.

Tags: flat-free tire, non-marking, pneumatic tire, tire sealant

This entry was posted on Friday, March 6th, 2009 at 3:26 am and is filed under Wheelchair. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.