Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Deflating inner tubes

Over the past 8 months I've had two occasions when a flat tyre resulted after about an hours high speed run on motorways and dual carriageways.

A front tyre on separate occasions deflated slowly and the fault was the join of the inflator to the tube.
The tyre fitter I used to replace the tubes suggested to cause was likely to be under inflation causing the tyre flexing to rub the join on the wheel rim. Adding that "modern" cars run at higher tyre pressures: erm yes I know!

Tyres are Toyo 165/80 TR15, new February this year could these and the fact that my inner tubes could have 8 years old, be a factor? (I did not think to have the inner tubes renewed at the same time as the tyres); this has now been done.

I run at 22psi checked before both journeys in my 1992.4/4. 1.6cc.with suplex.

Am I running to low a pressure? Any suggestions

22 psi sounds about right.....is it the speed or duration that is making it more noticeable.

Not sure why you hung on to old tubes in new tyres? That's most likely to be the issue.

The prime degrader of tyre and tube rubber is age, closely followed by ultra violet light. Add heat, wear and extremes of temperature and assuming there are no chafing or sharp edges inside the tyre carcass, you're on a loser!

It's hard to diagnose the cause remotely without seeing the point at which the tube gave way. If the pressures were too low, there would be evidence of chafing or movement around the places of conflict & I doubt the tyre fitter would be looking that close for you..

The other point to be aware of is that unless the tyres have been specifically manufactured to be fitted with inner tubes, the inner carcass of the tyre can be very rough and abrade the inner tube as the tyre flexes.

Certainly using 8 year-old tubes is a bad idea, and when replacing them try to find heavy-duty tubes, which can withstand the abrasion of the carcass. This can be easier said than done, I would call Paul Harris at Sutton Coldfield (0121 311 1969) for help

Finding Tubeless tyres is pretty much a non-starter I would think unless you went to a specialist like Longstone or Blockley - and I suspect they would only be available in vintage sizes.

The best solution in my view is to convert to tubeless fittings. The easy (but pricey) way to do this is to simply buy new wheels from MWS. This is what I did on my 1986 4/4 a couple of years ago.

The cheaper but more complex solution is to seal the inner rims yourself with a heavy-duty silicone sealant like Sikaflex. This is what MWS do to seal the rims and enable tubeless tyres to be fitted, but getting the inner rim properly degreased, and laying a nice smooth layer of sealant all the way round the wheel so that it doesn't leak is not something I fancied trying.

Fit new heavy duty tubes. I did ..... problem solved

On a car as light as a 4/4 , anywhere between 18 and 22 psi is about right for road use. If used on the track then go to a much higher number to prevent the tyre rolling off the rim, say 28 to 30 min.

As others have said heavy duty tubes are a first port of call , but even this may not help if the insides of the tyres have very abrasive surfaces.

Are you using rim bands inside the wheel to protect the spoke heads (I assume you have wires?) This can also help.

Long term , go for new wheels and fit tubeless tyres as per Tim (Hamwich)

With my 4/4, either 18 or 19 was the factory recommended pressure. I tried it, once, and swiftly inflated the tyres again.

After a lot of experimentation, I settled on 22 front, 23 rear and much to my surprise, these pressures were right for 165/82 (the tyres weren't labelled as such, but that's what they were) 185/65, 195/50 and 195/60.

Competition, minimum 28, maximum 32 and same front and back (most of the things taken out were behind the centre of gravity)

No off the new Tires are aproved for Tubes.
With Pirellis was some accident, the tires rib off the tubes.
I had to by new tubless wheels for my E Jag, because i dont get any tires for Tubes.

Manuel