Why is my tyre going down?????

[jberks]

I'm getting short of ideas now. Had my tyre refitted and resealed 3 times now but it keeps going down. Last time I thought we'd sorted it. Actualy found a small leak so refitted and filled with nitrogen and 2 days later it was still on 32psi. Bingo.
1 week later it was back down to 23psi :-(
So, ...it went back again today. I asked them to check for a leak and if rim corrosion was the cause, to just get the damn thing reconned.
They couldn't find a leak again so pumped it up to some silly pressure and left it all dayto see if it would seep. It stayed rock solid, didn't drop a lb. So they removed the tyre again and rechecked the rim for corrosion. 100% perfect.

They've refitted it again and I'll pop it back on tonight, but I'm not optomistic.
Given that it's fine on test, and apparently not leaking, the only thing I can think of now is that the tyre is somehow moving under load so it's ok stood in the garage or parked but lob it round a few corners and roundabouts and things start to go pear shaped.

Anyone had experience of such things?
Any other ideas?
help

 

[rf065]

I had a rear tyre on a motorcycle go flat once, luckily near a garage and only 6 miles from home. I blew it up at the garage and made my way home before it went flat again, but it never did go down again. Still can't explain it.

Russ

 

[television]

Its a privilege to help you sir,, did they put that black sealer in between the rim and the tyre, and really clean the rim with a wire brush first

 

[dave.robbo]

It may have a tiny hole somewhere in the tyre. When it's not under load, i.e. not at the bottom of the tyre, the rubber around the hole may seal it well enough to not leak.

In use, the hole may be opening and closing with every revolution, therby losing some pressure. And when you park, if the hole is at the bottom, it mey seep out overnight.

Just a thought, but a possibility.

A few years ago, I had a similar problem. Got fed up with it, so I went to a garage and got some Ultraseal fitted into the tyre. Never had a problem with it again. Check it out here.

I didn't use that garage, but it does tell you about the stuff...

 

[jibcl500]

J.
I had a similar problem turned out to be a hair line crack on the inner rim, with the wheel off the car never lost any air, on the car it would, I can only assume the fracture was stressed with the weight of the car on it.

With the tyre removed tap the inner area of the wheel, if it the sound changes as you tap in different places.
jib

 

[Mercedes 190E]

It is also not unknown for an alloy wheel to be slightly porous.

 

[roofless]

the valve might be iffy in that it hold's pressure then when you check it it might cause it to stick a bit & you have pressure loss the next time

 

[Juddian]

Upset the good lady J Berks by filling the bath with water and gradually work your way round the tyre till you find the leak, its still the best way to trace leaks.

If you do it yourself you can leave it ten minutes at a time on each section thats underwater, maybe a little washing up liquid in the water to create some bubbles too.

 

[television]

Upset the good lady J Berks by filling the bath with water and gradually work your way round the tyre till you find the leak, its still the best way to trace leaks.

If you do it yourself you can leave it ten minutes at a time on each section thats underwater, maybe a little washing up liquid in the water to create some bubbles too.

Its better if mr berks sat on the tyre while in the bath to put it under load

 

[Dave's E55 AMG]

This happened to me once it turned out to be a flat spot on the alloy wheel - probably from hitting a pot hole

 

[dragon]

Find that I have to check tyres more often fitted with alloys than with steels. Bound to need topping up air in alloys than in steels.

Most garages or tyre shops have a large tank of water for you to dump your wheel in to check for leak.

Puncture repair quite expensive, got done for £15 a time now.

 

[jberks]

Thanks all.
In answer to Malcolm, yes, they blathered some black stuff on (3 times now) and the rim is clean and shiny apparently with no noticable corrosion. They're one of the best fitting places in Leeds (IMHO) and are scratching their heads.
Since posting I haven't checked it yet - seems ok at the moment but if it's dropped a few lb I probably wouldn't notice. I'll pop a gauge on it tonight.
All this started when I pranged the old tyre so I am a touch suspicious about the wheel, but, the wheel took a slight knock but it was only a glancing blow as I just clipped the kerb a fraction. The tyre took virtually all of the impact. That tyre did stay up but had a bulge so I put a new one on and it's been troublesome ever since.
Its been in a bath at the garage a few times now. The time before this, they did find a small leak bubbling away on the inside of the rim but last time, absolutely nothing coming out, despite being up at 100lb. (I think thats what they said)

I did wonder whether I'd bent the wheel slightly but there is no vibration or other indication of anything out of kilter. They've done a visual check of the rim and it all looks ok. Certainly the outer edge is ok, with no visible flat spots.
I guess something wierd on the tyre may explain it. I'd say possible explanations from dave.robbo and jibcl500 sound possible and given the history Dave - was there any indication - or was it masked by the tyre?
If it persists, I'm thinking that what I may do is have them swap the tyres between 2 wheels (putting the tyres back where they came off, just on different wheels). Then if it's the tyre, it will stay where it is, and if it's the wheel, my flat will move across the car.


Also, as an aside, don't know why, but I guess as its hidden away under a fixed cover and it's a space saver, I'd never really looked at the spare. When I put it on, I figured as I was at home and the pump was handy I should check it. The sidewall says "Inflate to 60psi". There is nothing on the filler cap chart about it so I assumed thats the correct 'one size fits all' pressure fro a space saver.....it was 33psi. It seems that the dealer doesn't check them so I pose the question ....what's yours pumped up to??. When was the last time you checked yours?

 

[television]

My spare wheel is the folding flat wheel that has to be inflated before it can be used.

Just thinking about blowing the wheel to a very high pressure,,could this temporary close a gap or any porous part of the wheel

 

[rf065]

My spare is always at 60 psi

More important, is to use the bolts for the spare and not the normal wheel bolts.

Russ

 

[jberks]

My spare is always at 60 psi

More important, is to use the bolts for the spare and not the normal wheel bolts.

Russ

Hi Russ, Thanks for the 60psi confirmation.

On the bolts, very true and very important.... except - mine doesn't have different bolts and neither did my Friend's 2005 211. I assume they did away with this daft system sometime in 2004 or else the 17" wheeled versions have the short bolts anyway.

 

[rf065]

Hi Russ, Thanks for the 60psi confirmation.

On the bolts, very true and very important.... except - mine doesn't have different bolts and neither did my Friend's 2005 211. I assume they did away with this daft system sometime in 2004 or else the 17" wheeled versions have the short bolts anyway.

Mine is Dec 2005 & 17" wheels, but still has the short bolts for the spare, must be another explanation.

Russ

 

[Dave's E55 AMG]

The flat spot I had was only 0.1mm over a distance of about 65mm along the tyre seating groove, we only found it by spinning the wheel in a lathe and clocking the rim with a DTI.

 

[television]

Mine is Dec 2005 & 17" wheels, but still has the short bolts for the spare, must be another explanation.

Russ

Could it not be short bolts for steel wheels, my car is 2002 and has an alli spare

 

[dave.robbo]

I'd say possible explanations from dave.robbo and jibcl500 sound possible and given the history Dave - was there any indication - or was it masked by the tyre?

Absolutely no indication at all. Got it tested for leaks, and couldn't find anything, but the ultraseal did it's job for us!

 

[rf065]

Could it not be short bolts for steel wheels, my car is 2002 and has an alli spare

That sound likely, Malcolm. Space saver is steel afterall.
But Jberks must have alloys & steel spare too, with same bolts?

Russ