Don Horn wrote:

> Operating under the assumption that there are no dumb questions, just dumb
> questioners who want to get smarter, I need to backtrack a little on the
> split rim thing.
>
> What exactly is a split rim? Sounds like a 2-piece assembly that bolts
> together, thus requiring tube tires? How can I identify a split rim vs. a
> "conventional" one? I'm guessing my '65 Caravel with baby moon hubcaps has
> split rims, and suspect I might want to replace them, and likely the tires
> as well. Sounds like flats would be impossible to repair yourself, if
> they're that dangerous to work on.
>
> Speaking of repairing flats, which would be easier to repair on the road
> tubeless tires or tube tires on a non-split rim? If you have tubeless
> tires, can you find the puncture, remove the nail or cactus needle*, insert
> a plug and re-inflate, without removing the tire from the rim? Can you just
> put a tube into a tubeless tire (again without removing from the rim) and
> use it as a temporary fix?

Answers to those last three questions:
a) depends on your definition of "easier" - tubeless is quicker and easier *provided* the puncture is in the tread area and the bead hasn't come off the rim; otherwise tubed is equally quick and I think more certain
b) yes, provided the puncture is in the tread area and the bead hasn't come off the rim
c) no, to insert a tube you have to lift the front (outer) bead off over the rim, and "break" the lower one so it drops into the "well" of the rim; in other words, you need tire levers for this job. A tube is, however, a perfectly satisfactory "fix" and indeed the only possible one if the puncture is in the
sidewall area of the tire.

To find leaks you need to carry a small spray bottle of soapy water -- a couple of drops of dish washing liquid in a bottle of water will do the trick. Spray it on the tire and bubbles will appear wherever there's a leak.

I'll let the experts talk about split rims, I know what they are but have fortunately never had to deal with them. I've never done the Baja but have a certain experience of tire miseries in such places as the Sahara, Arabia, rural Spain and offroad in the American Southwest. Probably half a million miles
in such environments in various 4WD vehicles, with and without trailers. Horse trailers mostly. The following are very personal viewpoints which may not be shared by all experts!

1. Always use radial tires for offroad work. Radials have many virtues but in this context the main one is that on soft ground or when stuck in sand you can temporarily run them at very low pressures which increases the contact area and so allows you to drive over surfaces into which diagonal ply tires would sink hopelessly. I operated Range Rovers with Michelin radials, normal pressure 25 psi. In soft sand you can run them at 10 psi and if you know what you are doing you can actually drive up the slip face (soft side) of a sand dune. When you get out of the soft stuff of course you have to blow them up again pronto because at 10 psi they would very quickly be ruined if you drove fast or
over rough hard surfaces, rocks for instance.

There is one surface on which even letting down radials won't get you out of trouble. That is a salt flat ("sabkha" in Arabia, "chott" in North Africa, and I suspect some of the "playas" in this country though I have as yet no personal experience of them). Sometimes they appear safe and solid, and sometimes
they are, and sometimes they aren't. Even the local experts, such as Bedouin in Arabia, are often fooled. Some of them are bottomless, and even camels have sunk without trace. If you get bogged in that stuff you are unlikely to get out without a tow from another vehicle standing on solid ground - which may require a *very* long tow cable. So don't drive on it, except just possibly in the tracks of another vehicle which you know has made it safely to the other side. And even then not if that vehicle showed any signs of sinking in.

2. I don't like tubeless tires for offroad work because if you do get a flat you are often SOL. For a puncture in the tread area you have two options: plug or patch. Plug is much easier and requires less gear. You can insert the plug without removing the tire from the rim. If the bead is still seated you
can then reinflate the tire and be on your way. The patch is a better repair, but requires removing the tire from the rim. Not really difficult if you have two tire levers and know how to use them. The problem comes afterward, getting the bead to seat again. In tire shops they do that with a blast of air. The trouble is that any inflation device you are likely to have in the field won't deliver that kind of *volume* of air and with a low-volume electric air pump (the usual situation) it can be a real hassle getting the bead to seat. With a foot pump, even lower volume, good luck.

With a tubeless, radial tire even a very small puncture in the sidewall area means the tire is history. Tire shops are prohibited by liability considerations from repairing such punctures, and for good reason. Because of the way radial sidewalls "work" while rolling, a subsequent blowout is very likely.

Both of these problems (bead seating and sidewall punctures) can of course be circumvented in the field by putting a tube into the tubeless tire. That will get you down the road and to the end of your trip. Of course it will play hell with the balance of that wheel, but in most offroad work you aren't going fast enough for that to matter much (I'm not talking about OR racing here). You do have to be religiously careful to remove every trace of the puncturing thorn or spine before inserting the tube. Otherwise the tube will be destroyed in no time at all. When you get back to civilization and remove the tube, of course the sidewall-punctured or stonebruised tire is still scrap. One with a puncture
in the tread area can usually be repaired properly, with a patch, and the wheel re-balanced.

3. For reasons which will be evident from the foregoing, I found it most convenient to use tube-type, radial tires from the outset (I am a cheapskate and don't like throwing away expensive, almost new tires). When going offroad (which was most of the time during 20 years in Africa and the Middle East) I carried two spares, a pair of tire levers, several replacement tubes (top quality Michelin tubes cost less than ten bucks on the local market) and several "Camel" hot vulcanizing tube repair kits. I don't know whether those truly nifty kits are available in this country, because I never had occasion to look for them. The "Camel" kit is ingenious and very simple. There is a small screw clamp (you only need one of those) and the kit itself is a box rather larger than a pack of cigarettes, containing a grater, a number of patches and an equal number of vulcanizing pans. These latter are small metal pans with a flat smooth bottom and filled with a combustible material. You roughen the tube around the puncture with the grater, apply a patch (it has peel-off backing), set a pan on top of the patch, clamp the whole thing firmly together and put a match to the combustible in the pan. It burns, or rather smoulders, for several minutes. When everything has cooled off you remove the clamp and presto! a hot vulcanized patch. It works better than any cement-based system I have seen, the end result is a professional-quality patch which will last forever. The patches are so light they don't affect the wheel balance much, provided of course you take care to replace the tire on the rim in the exact same position as before (mark before removing!). If there are multiple patches you will want to
re-balance the wheel when opportunity offers. I once came back from a desert trip with 7 patches on one tube (told you I was a cheapskate). The spare tubes are for those not altogether infrequent occasions when the tube gets shredded while the tire is going flat. Mesquite thorns are especially good at that.

The trick to using tire levers is practice. It is a matter of skill, not of great strength nor of much use of a hammer (likely to damage sidewalls and/or beads). Out of necessity I got to the point where I could get a tire off the rim, and back again, almost as quickly as the boys in the tire shops with
their air-operated presses. On one hunting trip in Arabia we were driving mostly over sharp lava rocks and averaged 5 flats a day. That's practice.

John

Susi and John Burchard
Tepe Gawra Salukis
saluqi@ix.netcom.com