OT: likely cause of deflating tyre

[mike]

I had a tyre that was losing pressure slowly. It was getting near the wear indicators and the MOT was coming up so I kept topping it up for a few wee ks and arranged for the garage to replace it before it was MOTed last Frida y.

I noticed today the new tyre was looking deflated so I put the pressure gau ge on it and it was virtually flat.

The garage is pretty reliable and, as far as I know, the valve has been cha nged.

I can't get back there before Friday and I'll keep checking/topping up in t he meantime but I'm just wondering what combination of punctures, leaking v alves, unsuccessful fitting and damaged alloys would account for the old ty re leaking slowly and the new one leaking fast?

Is there anything obvious or is it just a matter of taking it back and lett ing them put it in the big bucket of water / fiddle with the valve?

I'm assuming that minor damage to an alloy wheel could be hard to spot but still sufficient to cause a leak? Are alloys repairable or do they have to be replaced?

Any advice appreciated.

[Tim Watts]

On Wednesday 10 July 2013 19:05 mike wrote in uk.d-i-y:

SWMBO's car had a screw in the tyre that was causing pressure loss from correct to about 1 bar down in a week.

[Bob Eager]

I once had a car where three wheels had tyres that deflated like that. It was flaking lacquer on the wheel...exacerbated when the tyre was changed.

[Dave Liquorice]

Different tyre but Sods 1st Law says the OP has picked up a nail/screw in the brand new tyre. Sods 2nd Law will mean said screw is outside the central 2/3rds(?) of the tread where a repair would be allowed.

I doubt the garage checked or cleaned the edges of the rim when they put the new tyre on. Just splashed some sealing gunge around the bead of the tyre and fitted it. I suspect there is a build up of crud on the rim preventing a seal forming.

[Bill]

In message , mike writes

That's what I would do.

I'm told that 2 wheels on my Disco have become "porous".

When I last had a tyre replaced, the local ATS said they had coated the inside with something (and perhaps used bead sealant), and that tyre seems to be holding up. They said it might work.

I just carry a reasonable electric pump in the back and use it from time to time on the other tyre.

I'm not really sure what makes alloy porous, or whether this is just a word used to formalise something that people don't understand

[fred]

In article , mike writes

Corrosion on the bead area of old alloys can cause pressure loss, I've had this on a very old set and decided to replace them with a set from a newer model of my car that came up at a good price. I spotted it when I was getting a puncture repair done and was surprised how dusty and rough the bead area had become. The fitter, who I trust, cleaned it up as best he could with a soft wire brush but I decided it was time to replace.

You can get rims re-finished and powder coated which should leave all surfaces sealed and baby smooth. I think it can be done quite reasonably.

Maybe try a post uk.rec.cars.maintenance

[Mr Pounder]

[Cash]

If nothing obvious such as nails etc in tyre, then it could simply be a defective seal between tyre and rim.

Old method of curing this - you could try inflating the tyre to around 40 -

50psi and hold for about a minute of so to tighten the rim to tyre seal and then deflate to the proper pressure.

If this doesn't work, then return to the garage asap as per your post.

Cash

[harryagain]

I noticed today the new tyre was looking deflated so I put the pressure gauge on it and it was virtually flat.

The garage is pretty reliable and, as far as I know, the valve has been changed.

I can't get back there before Friday and I'll keep checking/topping up in the meantime but I'm just wondering what combination of punctures, leaking valves, unsuccessful fitting and damaged alloys would account for the old tyre leaking slowly and the new one leaking fast?

Is there anything obvious or is it just a matter of taking it back and letting them put it in the big bucket of water / fiddle with the valve?

I'm assuming that minor damage to an alloy wheel could be hard to spot but still sufficient to cause a leak? Are alloys repairable or do they have to be replaced?

Any advice appreciated.

Remove tyre & spray with soapy water should be easy to find. The alloy is porous but should be laquered inside to fix this. If there is no puncture, it's likely a leak on rim/tyre junction. They had stuff to "glue" the tyre onto the rim in days gone by, worked well. No longer allowed to use it, dunno why. They normally smooth the rim with bit of fine sand paper now

Could also be a leak tyre valve body to rim.

[Broadback]

With all the pot holes country wide, is it not possible that the wheel is slightly deformed?

[Adrian]

Don't let it sit flat - that'll bugger the sidewalls up.

As others have said... Could be the inner rim being porous, due to failed lacquer. Could be corrosion on the bead causing the new tyre not to seat properly. Could be a bend in the rim. Could be a crack. Could even be as simple as a faulty new valve.

A waterbath should show it up, depending on how slow it actually is. By the sound of it, not very... I recently had one that was taking ~2 days to go from 30 to 20psi. Big bend in the inner rim (steel). But the garage did insist on checking, and a soapy mix on that bit of bead showed bubbles immediately.

Depends on the problem. If it is flaking lacquer or bead corrosion, then anything from cleaning and re-paint the inside through to a full refurb, depending on if you care about the cosmetics. If it's a bent inner rim, then check carefully - they're straightenable, but not as much so as steels. If it's a crack, then they're weldable, but it may be cheaper to bin and replace.

[F Murtz]

This is the most likely cause if tubeless, the valve stem should be replaced with new valve inserted.

[Bob Eager]

I remember taking one wheel at a time to a place in Tonbridge that was recommended to me. They did a beautiful refurb for me, and never had any further trouble.

[Alan Braggins]

[...]

As someone else already said, cleaning/polishing the inside of the rim with a wire brush can help that, at least temporarily.

The other old method was to use an inner tube, and not worry about whether the tyre sealed to the rim. Sadly not so easy to try....

[Dave Liquorice]

And with a tubless tyre and tube fitted probably would last very long. The insides of tubeless tyres are quite rough...

[polygonum]

I didn't think it was allowed to fit a tube to a tubeless tyre, not even a rim designed for a tubeless tyre. Could be wrong...

Yes - I do know it was often done in years gone by.

[Adrian]

I had a trailer tyre go down this afternoon.

Don't know how long it'd been sat under a tree, but quite a while. Dragged it out, put 30psi in the tyres, and started to fanny about with something. Both tyres were remoulds, of extreme ancientness, very very cracked. I was quite surprised they held air, tbh.

Before long, one sidewall had a hernia.

A little bit later, somebody fired a shotgun nearby. Oh, wait. It was the tyre...

Not a lot of doubt as to what caused that.

[RJH]

I had a cracked alloy wheel leading to a slowly deflating tyre - difficult to see as the crack was mainly concealed by the tyre bead, and on the inside.

Aside from whether it's wise to repair in any case, I had a number of opinions about method and using the right people. The alloy welding specialists didn't deal with tyres, and the tyre people didn't deal with welding. It all became such a performance I replaced the wheel.

[polygonum]

Funny how actively used tyres last much better than those left under trees or pretty much anywhere.

Found this advice:

[Adrian]

Oh, I think these would have LONG since been binned if they'd been in use...

I rather suspect a sizable multiple of years since it was last used - the hitch has actually seized solid. I'm just surprised the brakes hadn't seized on. They've probably seized off, instead.

Still, it's gone off to do duty dragging manure round a field, so these things are fine detail.