Losing Tyre Pressure

[John Anne]

Good Afternoon All,

 

I'm seeking advice on an annoying problem which has been going on for about 12 months now.

 

For some reason 2 of my 6 tyres refuse to retain the correct pressure. One of them runs at 55psi and the other 80psi - rear and front, just in case you were wondering. Once inflated they seem ok for a few days and then seem to slowly deflate over about 3 weeks. Each of them losing about 15psi. I dare not leave them longer than this, but I presume that they would continue to deflate.

 

In terms of trying to resolve the problem, I have checked the valves to make sure that they are tight, I've checked the tyre treads for foreign objects and punctures - this has revealed nothing (?)

 

As far as I know the tyres have never been removed from new ( 30 months) and are fitted to the standard steel rims. They have covered about 9000 miles.

 

Here's the questions:

Would it be worth paying to have these tyres removed, checked and re-fitted with new valves (?)

 

Is there any experience out there of using this 'gunk' type stuff that is supposed to coat the inside of the tyre/rim and seal minor tread punctures as they happen and also prevent pressure loss (?)

 

Any other (sensible) suggestions would be welcomed.

 

It's such a pain having to check the pressures everytime we go out and especially finding an air line that is accesible and can also cope with 80psi.

 

Thanks in anticipation.

John & Anne. :-) B-)

[Keithl]

Hi Folks,

 

I'd start by taking the wheel off and, if you've got a large enough container, dunking it under water and looking for traces of bubbles.

You could make a temporary container using a plastic sheet draped over planks or whatever you can find lying around.

Alternatively try spraying or brushing the entire rim and tyre with a soap solution and look for foaming.

And don't forget to check all around the valve at the same time.

 

HTH,

Keith.

 

PS and sorry but I've never used any of the 'tyre gunks'.

[BGD]

Are Kwik-Fit still doing their free tyre checks?

 

I had a similar problem on a car about 10 years ago....the Kwik-Fit Fitter took the wheel off, took the tyre off the rim, cleaned the rim and the bead wall, refitted with new valve, then rebalanced; and just charged me about 3 quid for the valve.

 

No more gradual deflation.

[lennyhb]

I'd got with Bruce & get them off the rims & the rims cleaned, the tyre fitters can apply a sealant on the rim before fitting.

[terryW]

"Is there any experience out there of using this 'gunk' type stuff that is supposed to coat the inside of the tyre/rim and seal minor tread punctures as they happen and also prevent pressure loss"

 

If you do use it check that it is suitable for all vehicles and not just 'off road' vehicles, also I have been told that once it's in the tyres you can't have them balanced, but I have just looked at an OKO version of the stuff and they make no mention of this point. They do quote maximum hole size of 7mm, I had it in the tyres of my last vehicle and if I ever had a puncture I never knew. In my case they were on Alloy wheels and not balanced.

 

[lennyhb]

By using the gunk type products you are masking the problem I would have thought it would be better to sort it properly for piece of mind.

[John Anne]

Thanks Keith, Bruce, Lenny & Terry,

 

Your thoughts are appreciated and on balance I think it is best to find the root cause of the problem and get it fixed.

 

For the sake of a few quid at Kwik Fit or somewhere similar it will be worth the peace of mind in the future. If only to get rid of the pain in the butt of checking tyre pressures every few days, not to mention the thought of a big blow out on the motorway - dread the thought :'( or waking up one morning on a site to find the MH sloping un-naturally.

 

A job for the weekend then, another excuse not to cut the grass :-)

 

Cheers Guys.

 

John & Anne.

[Guest Tracker]

The cause is often corrosion between the tyre sealing bead and the metal rim - especially alloy wheels.

 

The cure is simple - remove the tyre, clean up the rim and the tyre bead and reseat and reinflate it, preferably water testing it before refitting - if you are lucky - and this is what I would do first as I have done in the past - and it worked.

 

If you are unlucky you may have a porous tyre but I understand this is unusual - but not unknown?

 

If you are very unlucky you may have porous wheels and I am not aware of any other cure for that than a tube in the tyre.

 

I don't know if there is a sealant that will seal a porous wheel or whether it can be painted once proven?

[Derek Uzzell]

John & Anne

 

As you are using 80psi as your front tyres' inflation pressure, your tyre-valves should be the high-pressure type and, if that's the case, quite possibly the metal clamp-in variety. If you have got clamp-in valves, it's possible that your two wheels are losing air at the valve's base. In order to avoid damaging the rubber 'washer' that seals the base of a clamp-in valve at the inner side of the wheel rim, particular care needs to be taken when fitting such valves not to overtighten the outer clamping nut that screws down the threaded exterior of the valve stem.

 

As Keithl suggests, if you brush soap solution liberally round the base of the valve, you should be able to detect whether or not there's a leak there. It's worth carrying out this simple test before taking wheels off or seeking professional assistance. If a clamp-in valve's base-washer begins to leak, then tightening the clamping nut is unlikely to help matters - in fact, it's just as likely to worsen the situation. Base-washers differ in design and a leaking base-washer will normally demand that the complete valve be replaced. It's also worth highlighting that tyre fitting outlets may well not keep clamp-in valves of the type used on motorhomes as stock items.

[John Anne]

Thanks Derek & Tracker,

 

I had not realised that 80psi called for special valves, I must admit the ones in the front wheels (80psi) look like the standard type so I will get these checked at a commercial tyre fitters.

 

A rear tyre (55psi) is the other one losing pressure so I presume that a standard valve type is acceptable (?) . Needless to say I did not manage to ge out of cutting the grass this weekend - her in doors had the final say and getting the tyres sorted lost (!)

 

Good advice though guys, I'm wiser now and more confident in getting it sorted - thanks again.

 

Cheers,

John & Anne.

[Derek Uzzell]

This is an earlier forum thread that may be useful:

 

http://www.outandaboutlive.co.uk/forums/forums/thread-view.asp?tid=20832&posts=7

 

The norm would be to have every wheel on a motorhome fitted with a valve-type capable of handing the highest inflation pressure that would be used for any of the wheels. This will allow any of the wheels to be fitted in any of the vehicle's axles irrespective of the inflation pressure appropriate to the axle.

 

Certainly, when 'camping-car' tyres are fitted, as these tyres are designed to cope with inflation pressures well beyond the design-limit of a standard snap-in valve, it's usual for a metal clamp-in valve to be used. In fact, Michelin's technical-data handbook used to carry (and may well still carry) an instruction "USE METAL VALVES" relating to their camping-car tyres.

[casey]

Hi all,

while having new tyres fitted to car today i asked fitter how much to remove all tyres and valves and refit/reseal, and he asked have i tried filling with nitrogen ?? he said they have a machine which does this and is the cheaper option to start with. he is a tugger and has done his caravan wheels without anymore problems. costs about £4.

will have mine done, hope it goes like a bomb !!

casey.

[casey]

Hi all,

while having new tyres fitted to car today i asked fitter how much to remove all tyres and valves and refit/reseal, and he asked have i tried filling with nitrogen ?? he said they have a machine which does this and is the cheaper option to start with. he is a tugger and has done his caravan wheels without anymore problems. costs about £4.

will have mine done, hope it goes like a bomb !!

casey.

[Derek Uzzell]

casey - 2011-04-21 6:10 PM

 

Hi all,

while having new tyres fitted to car today i asked fitter how much to remove all tyres and valves and refit/reseal, and he asked have i tried filling with nitrogen ?? he said they have a machine which does this and is the cheaper option to start with. he is a tugger and has done his caravan wheels without anymore problems. costs about £4.

will have mine done, hope it goes like a bomb !!

casey.

 

This is the most recent earlier forum thread mentioning tyre-inflation via nitrogen. In that thread my posting of 3 December 2009 contains links to very negative comments by Tyresave and the AA:

 

http://www.outandaboutlive.co.uk/forums/forums/thread-view.asp?tid=17890&posts=26

 

One thing is certain - if a tyre is losing pressure significantly (as two of John and Anne's tyres were) then inflating the tyre with nitrogen won't address that problem. There are potential benefits using nitrogen for specialised applications, but it won't correct a defective valve, a leaking rim-to-tyre seal, a porous or cracked wheel or physical tyre-damage like a puncture.

 

If you haven't already spent your £4-per-wheel, I suggest you don't bother.