Tubeless tyres- where is the 'seal'?

You could have cleaned up the rim down to bare metal in the offending part of the rim, applied primer and repainted for a good seal. Might be worth doing to the old rim in readiness for the other side failing.

I 'splashed out' and replaced all three, only to find the other two were fine ;-( Having said that, for peace of mind, it was worth the money- I don't want to be worrying about tyres etc when towing. (I don't mess around with safety.)

Correct. This seal is in fact remarkably tolerant of dirt, debris, corrosion, etc, especially when the tyre is fitted with the lubricating grease used by garages.

Don't know about legality of inner tubes but AFAIK they are still required for wheels with wire spokes.

If it is an alloy wheel, another failure process can be minor cracking and/or tracking of a crack through the inevitable regions of porosity in a casting.

In my experience rusted steel rims can often be recovered by sufficiently vigourous wire brushing. Repainting with a sufficiently thick paint may also solve the problem. Perhaps forever, with two part epoxy, or for a few years with hammerite.

Think they use something more akin to a contact glue these days.

When having new tyres fitted to my old car, the fitter got a phone call in the middle of doing them. He'd already applied the gunge to one wheel. And it was some time afterwards before he fitted that tyre. And it leaked. ;-) None of the other three did.

Or perhaps it had just "dried out" a bit? Don't know whether they are solvent or water-based.

This one is described as "quick drying" (seems to be a soap)

Two reasons not to use inner tubes: if you get a nail in the tyre - or, more likely these days - one of those viciously sharp modern woodscrews, a tubed tyre will deflate very much faster, losing air through the valve hole in the rim; and some tyres, unless marked "TT", have moulding lines on their inside surface which can wear holes in tubes. I've had this on a Range Rover.

If your rims aren't designed for tubeless, they may not have the shallow humps on their bead seat area which are claimed to reduce the chance of a tyre becoming dislodged under extreme conditions. I made some effort a few years ago to find any recorded incident where this had happened, and failed. My judgement was that rapid deflation posed a bigger risk to me than bead separation, so I fitted tubeless tyres to my classics. YMMV.

Alloy wheels were invented by the devil, for use on his chariots, so if you can't get them to seal properly, it serves you right.

Kevin

Thank you.

I wasn?t thinking of fitting tubes I was just curious if my memory that fitting then to tubeless tyres was banned.

The rims on the trailer are steel.

We?ve alloys on a couple of cars, they are normally fine. Motorhome has steel rims.