2000 Yaris with alloy wheels.
Just found one tyre at 19 psi not 33 psi on a routine check so I am looking for a reason.
It is a new tyre one month old Continental and has done 200 easy miles then unused for two weeks
Before any further use it will go back to the tyre depot for professional checking next week.
What could be the problem.
1. Depot under inflated it. Unlikely
Three new tyres were fitted to match the existing almost new Conti and no handling problems.
2. Some toe rag let it down. I do not think so
3. Puncture. Close examination found nothing so no suds used.
4. Soap suds on valve. No indications
5. Soap suds on valve seat. No indications.
6. Soap suds around both beads with the wheel flat. Nothing
That leaves me with a couple of thoughts.
A. Tyre is not seated properly when driven / flexed.
B. The wheel is porous.
The alloy has some corrosion but nothing that seems drastic.
I put some suds on the alloy but no signs of anything.
One of the old tyres did loose pressure but was put down to its age. Thus, unfortunately I did not identify which wheel prior to the tyre change.
Are there any other posibilities?
It is now up to 33psi and I will monitor it for a few undriven days.
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The trye may not have "popped" onto the rim properly when fitted and pumped up and was loosing air but useage has sorted than and it may now be air tight. I have also come across tyres that onlt leak when the tyre is resting on the a particular area of the tyre, againg lack of rim/bead seal but difficult to find. Monitor and report back. Regards Peter
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Peter. Thanks for those suggestions.
First of all I will watch and monitor it for a few days in situ.
It is sitting on the drive awaiting to be insured again so I cannot drive it at present.
I will certainly report back.
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Years ago I had a Golf with alloys and 2 of them were porous. One would go flat, over a period of time, the other would go down to about 10 psi and then not leak any more. I identified the problem by puttin the whole wheel/tyre combo in a bath and seeing where the bubbles were from; it turned out that they came from the metal casting and not any valve or tyre bead area. Replaced under warranty.
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Armitage Shanks. Thanks for info.
If the problem continues I will get the depot to dunk it as the tyre is so new.
I will call in to see the helpful manager and advise him of the problem so it is logged as early as possible.
I had the MoT done 24 hours after fitting the tyre so the mileage can be reasonably verified.
I would not expect to get help from Toyota as it is a bit old now - V reg.
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Usually with alloys as already said the tyre seat on the bead has a bit of rubber left from the previous tyre that allows air to leak out particularly when the tyre is parked up at a certain position.
The other cause could be continental weights have been used that are opening up the bead gap.
You may also have a puncture.
The solution is get the tyre off the rim and get the tyre fitter to clean up the rim of the alloy with a good stiff wire brush any competant tyre fitter knows to do this if one wheel is losing pressure, assuming no foreign object is in tyre.
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"a little man in a big world/"
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I have a similar problem with one of the front tyres on my Peugeot 306. I replaced the two front tyres nearly a year ago, with nearly new tyres off my mate's mondeo- all was well for about 3 months when I noticed the o/s front tyre looking a little low. Checked pressure which was 15 psi instead of the recommended 30 psi, so re-inflated it to 30 psi- only for it to go down to below 20 again a few days later. Took to a local tyre dealer who inspected it and found no puncture, removed it, re-seated it and replaced the valve. All was fine for 2 months until it went down to below 20 psi and have been inflating it weekly ever since. Will get it checked again soon.
Martin
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A wire brush. Not on my alloys they don't. This may fix the leak but a couple of months later the corrosion of the exposed alloy will leak a lot more. Alloys are only powder coated but so clean with a good solvent will remove and debris. The wire brush is for when the power coat has lifted and allowing air out and the fitters remove all the loose junk and apply a rubberoid solution to the bead seal area. Regards Peter
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i think you will find that a 2000 yaris will need the wire brush Peter D i was trying to give reasons for air loss rather than how to repair as this is the tyre mans job, i also forgot to say get the tyre filled with nitrogen when done and have a competition valve fitted as these are far superior in the long term to cheap nasty commercial rubber ones
I nearly forgot make sure that the compressor the fitter is using if he fills the tyre with compressed air has not just been filled as the air will be hotter than ambient temperature and may give a false reading on a tyre pressure guage,im not going to even ask if the guage is regularly checked by the local air product specialists.
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\"a little man in a big world/\"
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I had this problem recently. Came out and found one of my month-old front tyres was half the pressure it should be (on an alloy rim). Tyre services couldn't find a puncture, so they just pumped it up to 55 psi and then back down to the normal pressure, all was okay ever since.
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The tyres on my Metro would sometimes leak around the rim. It turned out there was a sticky label on the tyre just under the rim that had detoriated.
Removing the rest of the label fixed the problem.
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An update on the problem.
I returned to the the tyre depot.
They did all the leak tests, checked the valve and found no tyre damage so all checks found nothing.
There did appear to be a small patch of corrosion on the inner rim which looked like it was caused by a weight clip.
They certainly used the rubberoid solution before refitting the tyre.
Since then it seems to have lost just one or two PSI.
I will continue to monitor the pressure.
Thanks for all the responses.
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we had this problem on our old taxi 405 and in the end we went to a scrap dealer and replaced the wheel itself and put the old tyre back on and hey presto no problems after that!
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