Innertubes

[Fozz]

Have just used up loads of spit on the " time honoured method", (didn't ask because I thought this was taking the wheels off an laying them flat ) couldn't see any bubbles, was hard to get spit to stay on the valve stem long enough!
Valve stems are all very shiny and new, haven't got a tool atm to tighten them but am off to Halfords in a mo to get a jack, so will have a look.
I bought the latest "Practical Classics" which had an article about tyres on classic cars, and it says that " all 80 and 70 per cent aspect ratio radial tyres can run tubes. Anything with a lower profile than 70 per cent cannot take tubes" My tyres are marked 155/80 R14 80S, so does this mean 80 per cent ratio? Will have to go back to tyre fitters next week to say yes or no to these ****tubes!

[bmcecosse]

Never heard so much rubbish as that statement re tubes from Pratical Classics! What a laugh!!

Any tyre can take a tube - BUT the modern method of curing tyres does use an internal bladder which is quite heavily ribbed - and this makes rib marks in the tubeless liner of the tyre (all sizes - not just less than 70 profile !!!) - so there is a risk these may 'fret' against the tube over time leading to failure. The leaks will NOT be due to rims/cornering - but may indeed be due to rusty rims not sealing properly. Could also be they have damaged the beads of the tyres when fitting them of course - if they nicked the soft rubber! Rims should be clean and de-rusted - and smeared with slippery substance (swarfega works well) - not glue! - when fitting the tyres. Leaks at the valve can be around the base of the valve - in fact that's the most likely place - again due to rust on the wheel rim where the valve pulls through. This needs to be clean and non-rusty - on both sides. Test by soap water around the valve base - and wiggle the valve about by hand - any bubbles spell trouble. And of course - as mentioned already - if the wheels are rivetted construction they can leak at the rivets - tubes are probably the only sensible answer if that's the case - although you could try the injectable tyre sealer sold for roadside puncture repairs - although I doubt it would last long.

[Roni]

Back in the 70's, when I was a tyre fitter, the change over to tubeless was in full flight. I remember that the most common cause of slow leaks was rust on the rim. We used to spin the wheel up on the wheel balancer and wire brush the wheel quite often. Another cause of slow leaks was often the rivets but more likely the tubeless valve where it mounted into the base, once again corrosion related.
Fitting tubes into tubeless tyres was more successful on some makes of tyre than others, depending on how sharp the internal ribs were. Short of smoothing the ribs off we would use french chalk to lubricate the tube/tyre interface. It was a lot easier to try and stay tubeless. A useful tip to be doubly sure your valve core doesn't leak is to use a metal valve cap. They hold pressure quite well should the core start leaking.
Our main concern in fitting tubeless tyres to a non tubeless rim was the lack of retaining humps on the rim. At normal pressures it was not a problem but at lower pressures, e.g. slow puncture, the bead could move from the rim resulting in a sudden depressurisation and much vehicle instability. Thinking about it, a puncture in a tube type tyre was seldom slow and would cause similar problems.
We also had a couple of rather sad jokes when people would come in -
"I've got a slow leak." "you need to see a doctor, not us"
"I've got a slow leak." "Ive got a fast cabbage, do you want a race?"
We did always fix the leak.