Tubeless Tires

[dpep]

I ran tubes in tubeless tires for over 20 years and well over 100,000 miles. I hate changing motorcycle tires. I am more than glad to pay somebody a few bucks to do it, but many/most shops won't mount a tire without a tube unless the rim is marked tubeless. I have finally gotten tubeless rims on both front and rear of my 850, so I should be free of tubes from now on. But it wasn't that big a deal when I was using them. A little extra expense when I bought tires (always got new tubes at the same time), and there is that chance of more rapid deflation. But if it were me I would not go to the trouble of removing the tubesthat were were already mounted in the tires.

[Matt K]

Thanks Dpep. I guess I will wait until it is time for new tires!

[Roadwarrior]

I've had both, and I like tube tires. With tubless tires, the tires sit on the rims bead very tight, making it very difficult to change a tire without a tire machine. With tubless tires I can change the tires myself with a pair of tire irons, which saves me money on tire changes. As far as flats go, yes you can plug a tubeless tire from the outside, but then you need to replace the tire. With tube tires, all I do is pop one side of the tire off of the bead where the hole is, pull out the tube at that point, patch it, then put it all back together. When I'm done patching the tube the tire is still good to go.

Also, even though people say you should replace the tubes every time you get a new tire, I usually don't unless there are signs of wear on the tube.

[themess]

Rubber is porous to air. Two major factors in porosity are the kind of rubber and how it is 'filled'. Sone of the least porous types of rubber are butyl, chlorobutyl, and bromobutyl. Butyl is used for tubes. Tubeless tires have thin layers of either a chlorobutyl or bromobutyl 'innerliner' as the innermost layer. Both chlorobutyl and bromobutyl can chemically bond the the styrene-butadiene/natural rubber blends that are next, but butyl rubber cannot.

Innerliner must wrap around the bead, to prevent air from escaping between the bead and the rim. But innerliner is relatively fragile, so it is protected by another layer or two of tougher rubber. Some of these layers might have tire cord in them, which can bleed air very quickly if it is in the wrong place. The order in which these layers are placed is critical to air retention.

Tires that rely on inner tubes usually leak air faster than properly mounted tubeless tires on good rims. I once had steel valves installed on a my car rims with a new set of all weather tires. The size of the stems prevented my from putting an air chuck on them, although I could check the pressure. I decided to not go back for remounting until the pressure was below spec. I wore the tires out first, two years later.

Since the tire bead must match the rim almost perfectly, the profile matters. Here, my memory isn't sharp. I believe that the profile of car rims changed a bit when tubeless tires were adopted. Controlling the profile of both the bead and the rim certainly became very important. I vaguely recall something to the effect that Suzuki aluminum wheels had a tubeless profile from the beginning, even though for the first year or two they weren't marked as tubeless because the porosity issue hadn't been settled. It isn't critical if the bead and rim profiles don't match as well when tubes are used.

Tubes are not generally recommended when used with tubeless tires on tubeless wheels. Heat build-up can destroy tires. The extra layer of rubber in an innertube holds, heat, and the slight rubbing between the tube and the tire also add heat. Innerliner does an excellent job of holding air, a far better job than a tube in most circumstances. If I recall correctly, there are special tubes to be used inside tubeless tires.

If wheels are corroded or dented, or if beads are kinked, a tight seal is not likely. If a tire is mounted or dismounted poorly, the mating surface of the wheel can be scratched or otherwise damaged. Removing a tire usually kinks the bead slightly, unless it is done with great care. Rust on the mating surface can also result in relatively fast air leaks.

Tire manufacturers routinely pull samples for "wheel tests" run according to a DOT schedule. The tire is pressed against a steel wheel, about 8 or 10 feet in diameter, that runs off of an electric motor. After a warmup, the tires are run at desert temperatures with increasing speeds and loads until they blow up. Everything is in a steel cage but it is still frightening to be around when it explodes.