Tubes in tubeless tyres

[mike]

I recieved an "advisery" at my latest MOT that tubes in tubeless tyres was not approved . The wheels of my 1969 elan are rivetted and may not be airtight and most freely availible tyres in a suitable size for our standard cars are tubeless type constructions. I use a good type of tube in the tyre. The car was not failed for this point or any other.
I have owned the car for 34 years and this has never been an issuie before. What are other members views on this and has anyone else experienced this in recent MOTs?

[stuartgb100]

Mike,

Your timely question may be of use to me.

I've got leaking XAS FF tyres on Minilites on my Sprint. When I bought them, Minilite said tubes were not necessary, and my tyre fitter said the rims are not 'lipped' to take tubes.

Spent 2 hours unsuccessfully trying to talk to Minilite today.

Regards,
Stuart.

[richardcox_lotus]

I've been using tubes for years on my SP10s as the wheels are v. old & don't hold pressure.

Never ever ever had an issue with the MOT. Next April should be interesting !

One point is I have had, in total, 3 tubes fail (over a period of years). I believe this is down to the internal construction of the tyres, so they "dig in" a bit more to the tube.

Damned if you do, damned if you don't.............

[poiuyt]

You used to be able to buy special tubes for radial tires but since almost all tires are tubless today they are probably no longer available.

Can you seal the inside surface of the wheel? I know there are substances that can be use in motorcycles to seal and flats that may occur. Maybe you can use something like this in the car's tires.

Steve B.

[cliveyboy]

Older type alloy wheels can have a tendency to go porous.
You can get them sealed. The tyres are removed and the inside coated with a glorified paint.
If you are loosing air it might be worth trying to figure out where from.
Three culprits:- Porosity, bad seal on rims from corosion or damage, and leaking valve.
Most of the leaks I have had on old minilites etc are not porosity but bad sealing. Usually removing the tyre and lightly sanding the rims to remove corrosion or flaking lacquer works. I have also had leaking valves where they are not sealed to the wheel properly.
A bit of soapy water (washing up liquid) sprayed onto the wheels and left for a few minutes usually shows up the leaks.

Clive

[Dave-M]

Just as a point of interest. Washing up liquid is bulked up with salt and it's not a good idea to use anywhere near metal. Hand soap in warm water is best.
Regards
Dave

[GrUmPyBoDgEr]

Many years ago I was informed that the interior surface of tubeless tyres is too rough & could cause problems for tubes fitted into them.
Old wives tale
John

[rgh0]

Tubeless tyres have an inner layer of butyl rubber which is a very impermeable type of rubber in order to hold the air in. This is the same type of rubber as tubes are made of so I dont think inner roughness of tubeless tyres is a real problem.

In racing conventional wisdom is to run both tube and tubeless tyres without tubes. The rational is that under racing stresses the tyre can rotate on the rim and this can drag the tube with it shearing off the valve and leading to a sudden deflation. I know some racing guys who regularly mark their tyre to monitor for potential rotation and do observe it at times especially when running at low tyre pressures. I run the tube type Hoosiers without tubes and just have to top them up regularly as they loose pressure in a couple of days.

I do not know about any real technical reason why a tubeless tyre could not be fitted with a tube provide the tube was properly sized and the use was normal road use at normal road pressures. ONe reason for such a MOT regulation could be around stopping people repairing a puncture tubeless tyre by fitting a tube which would be unsafe if the puncture damged the construction of the tubeless tyre or if the hole in tyre was not properly repaired.

regards
Rohan

[andy73sprint]

My Sprint sucessfully negotiated the MOT on saturday without query on it's tyres with tubes. That said I didn't volunteer that it had any. The tester is a neighbour and he knows what I get up to in and on it each year and has kindly kept me up to date on any changes. The only point of note was a high level of hydro carbons but as I hadn't given it a a good run out should easily rectify itself.

Hope this helps.

Andy

[Emma-Knight]

The XAS FF should be run with tubes - it says on the tire sides. Also, in Germany, single hump steel rims have to be run with tubes, as they could popp down from the shoulder on sharp cornering.

[Tonyw]

Ladies & Gent's,

The nitrogen molocules are larger that air and tend not to leak as much, tyres run cooler as well, worth trying.

Tony W

[jeff jackson]

I have tubes on my +2 alloys. Been on around 5 years never lost any air. Before they were always going flat.
I'm not sure thw mot man even noticed.
Jeff 72+2

[CBUEB1771]

Ladies & Gent's,

The nitrogen molocules are larger that air and tend not to leak as much, tyres run cooler as well, worth trying.

Tony W

The choice of nitrogen v. air has been debated over and over again and basics are often forgotten. Dry air is composed of about 78% nitrogen, just over 20% oxygen and bits of carbon dioxide, argon and other trace gases. If you have a source of really dry compressed air there isn't much to differentiate nitrogen from air from the perspectives of leakage or tire temperature. The molecular radius for nitrogen is a few percent larger than for oxygen. Given this small difference and the predominance of nitrogen in air there can't be any real difference in leakage rates. The temperature of a tire is completely dominated by work input and convective cooling on the outside, at least at steady state operation. What is inside the tire might have a small effect on temperature change in response to transient loads. Here again there isn't much to choose from between nitrogen and air. The heat capacity of the gas in a tire is the product of the density and specific heat of the gases in question. The product of density and specific heat air essentially the same for nitrogen and oxygen, and by extension for dry air as well. Nonetheless there are good reasons to use nitrogen. The interior of a tire will degrade more slowly in the absence of oxygen, of course this does nothing for the outside of the tire. Probably the best reason to use nitrogen is the lower water content, assuming the nitrogen comes from a reputable air reduction manufacturer. If compressed air is not dried adequately there might be enough water to condense and evaporate as a tire goes through cooling and heating cycles. This will lead to relatively large changes in tire pressure going from cold to hot.

[sk178ta]

I`ve often wondered why, in F1 for example, they don`t fill the tyres with helium or some other light gas. Reducing outboard weight and unsprung weight, in particular. No doubt there is a good reason.
Jim

[CBUEB1771]

I`ve often wondered why, in F1 for example, they don`t fill the tyres with helium or some other light gas. Reducing outboard weight and unsprung weight, in particular. No doubt there is a good reason.
Jim

Now this is a case where molecule size and leakage really come into play. Looking at the Periodic Table we find we are restricted to helium and hydrogen for reasonably convenient materials that are gaseous at standard pressure and temperature and are lighter than air. Hydrogen has a pretty obvious downside, recalling the Hindenburg. Helium has both small atomic radius and is monatomic. Helium even diffuses out of metal containers so it probably wouldn't stay in a tire for very long.