H: Hubs, Wheels and Tyres Quality of Inner Tubes

[Albervin]

Have owned my Comet for 61 years now and seem to remember that in the past the tyres maintained pressure for many months.
Over the last few years however I have found that they rapidly lose pressure - dropping from say 30psi to 20 psi in a couple of weeks.
I ride the bike most weeks all year round but have to check and re-inflate my tyres most times I take it out !!
I have renewed the tubes, tyres and pressure caps a few times in the last 10 years or so and hoped that pressure would be maintained, but this has not been so and I have a similar problem with a 1976 Suzuki with tubed tyres.
Do the tube manufacturers now use some much more porous and probably cheaper material now to make tubes - bearing in mind also that with tubeless tyres now much more common, there is probably less demand for a good product?
I believed that the tubes I have used were from a reputable manufacturer, but has anyone had a similar problem and then found a manufacturer whose tubes are not porous please?
Matty

Yes. in short. You have to specify MX tubes or buy Metzeler or genuine French Michelin. Some Dunlop tubes are rubbish . I have had an issue with a front tube for years; loses 10 psi in two weeks while the rear holds for nearly two months. A bit hit and miss so always check before going out.

 

[ernie]

Vintage Tyres do a "Redwing" heavy duty tube which seems to be holding up. Made in the EU and cheap too! Michelin Airstop for the front also holding. I fit nut and washer inside on the Michelin because it has a more fragile valve stem fixing. Continental and V-Rubber tend to leak slowly, even with anti-puncture gloop inside! Remember to use lots of talc - baby powder - when fitting a tube.

 

[Colin]

Whatever you do don't fit Butyl tubes, they will not puncture exactly, they will split right along with disastrous loss of air. Real rubber tubes may leak a little but generally they will puncture rather than split

 

[Colin]

Come on Matty, you have AT LEAST 18 good years riding

 

[Texas John]

I have written posts on this and other forums, looking for tubes that do not leak. I have a bike with 40 Year old tubes in the garage that holds air better than any of my new ones. Tried 3 different tubes on one bike I am working on, and all leaked 10 PSI or more in a month, including 2 that were Heavy Duty MX type tubes. Replaced valve cores in them too. No joy! Wish I had a solution. Not enough time nor money to try every brand of tube out there.

 

[vibrac]

Perhaps when the construction and use regulations catch up with modern technology we can all have mousse inserts no more blowing up

 

[Matty]

Hi
I know this subject of tubed tyres losing pressure has been around for a long time but found an Article from Bennetts insurance (mainly about tyre safety) which states that "modern" tube rubber is in fact slightly porous so that one must expect some loss of air.
I have an old Suzuki (1976) with tubed cast mag wheels which loses around 5 lbs a week on both wheels and my Comet loses the same.

An insert from the Bennett article is below which probably explains the pressure losses even though I am using best quality Michelin tubes.
So I guess we will just have to always check the pressures before we use the bikes with tubed tyres.

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Below is a copy of an email I sent on the subject to some VVMCC Members who had also been having slow tyre deflation problems.

I have been worried why my tubed tyres always lost pressure over a few weeks and have found this article from Bennetts insurance which would seem to explain why modern tubes leak a bit of air.

Years ago tubed tyres would keep their pressure for months or years – many barn finds still had the tyres fully inflated.

So it seems that fitting new tubes on my Vincent to stop the slow deflation was probably a waste of time and would explain why even my tubed tyres on the Suzuki lose some pressure in a week or two.

Please see the extract below from an article, though the full text can be seen on the link at the end of the email



What is the difference between tube and tubeless tyres?

Simply put, a single layer of material on the inside of the tyre’s carcass.

All the materials used in a tyre are about performance – a balance of grip, flexibility and durability. It may surprise you to hear that the ideal mix of rubber is actually porous, so will slowly leak air. In the past, this was overcome by fitting a tube with a completely different rubber mix that would contain the air much better and have little effect on the overall performance of the tyre.

The biggest issue with this design is that if it’s subjected to a puncture, the tube will lose all of its air suddenly, which would have typically escaped rapidly through the spoke heads on the wheel. Rapid deflation of a tyre on any vehicle is not good, particularly when travelling at speed.

Created predominantly with safety in mind, the tubeless tyre was designed by taking a section of tube material and making a single continuous layer on the inside of the tyre carcass, and also saving weight.

Of course, a tubeless tyre can still be punctured, but the offending object usually stays stuck in the tread and the tyre deflates slowly, giving the rider an opportunity to slow down. At the same time, cast wheels mean spokes are no longer needed, so the entire unit has become sealed.

Now, instead of manufacturing both tubed and tubeless tyres in the same size, most companies only make tubeless, and recommend that tubes can be fitted if required. The disadvantage to this is that it adds additional weight to the total wheel assembly, which can lead to more heat generation, which ultimately means faster tyre wear.

If a tyre states that it is ‘tube type’, then it will have no tubeless liner, so it will not hold air and therefore must be fitted with an inner tube.



https://www.bennetts.co.uk/bikesocial/news-and-views/advice/bike-maintenance/bikesocials-complete-guide-to-motorcycle-tyres

Matty

 

[Old Bill]

Well that article certainly answers a lot of questions, but l will throw a spanner in the works with this observation. Whenever l take a bike out l check and invariably inflate the tyres as some of my machines are rarely ridden, however my son and l usually tour for a month and l can only remember having to add air maybe once? No l don't understand it either but l will be the first to admit that modern rubber provides far better grip at the expense of longevity: no tour this year mind so its back to the daily checks. Mind how you go..........

 

[Matty]

Yes I use an Avon roadrider (which is really a tubeless Tyre) on the rear of the Comet and it has a rounder profile for much longer, and makes the bike grip and handle much better than the older block treaded tyres.
We've been round this before, but remember to check that the small lable which used to be put inside the tubeless tyres is removed because otherwise it will chew into the tube and cause a puncture - I don't think Avon now use this lable after many complaints about damaged tubes and punctures..

 

[Monkeypants]

It was suggested to me that the very best tubes are the heavy duty Michelin MX tubes.
I gave them a try but aside from being awkward to fit, they lost air at a much higher rate than the cheap vinyl tubes.
The Michelin airstop seems OK, but no luck with the very heavy MX tubes, which are made from real rubber, apparently quite porous.

Glen