Slow Puncture?

[sproutdreamer]

One of my tyres has a slow leak about 4psi per week. I have had the wheel off and dosed it with very soapy liquid around the rims both sides and all over the tyre and the valve but cannot spot anything.The tyre is only about 2 years old and perhaps 3k miles. My assumption was that the rim was a bit corroded so the tyre was not seating perfectly but I would have expected to see a leek. Any ideas and what to do with it?

I have just read an AutoExpress article that says that manesium alloy wheels can be quite porrous - I did not know that!

[flash22]

The alloy may have gone porous, it is common on all sorts of marques tbh

replace the alloy or have it properly referb'd not just the face painted

[Stivino]

You'll have to be very patient to see anything with such a small leak. 

[sproutdreamer]

Thanks, what is the best way of refurbishing a porous alloy wheel rim?

[Stivino]

I wouldn't assume that it is porous.  I'd take it off and test it again, it might take a long time to see anything with such a small leak.

[sproutdreamer]

It is off the car but still cannot see anything? I was thinking of getting local tyre place to take it off for me, I will refurbish and then getting the tyre refitted and balanced.

 

[Stivino]

Put some soapy on one side, leave it for an hour or so, if you don't see anything, do the other side and repeat.  Have a good look at the tread and soapy that too.

Your wheels are more likely to be aluminium alloy other than magnesium alloys. 

I don't think the metal will be porous, it will be coming from the bead or you have something in the tread.

[Madasafish]

Happens on ours. Corroded rims.

Remove tyre, wire brush with electric drill - all seating areas.My local tyre fitting centre £10 per wheel

[mrpj]

Or, do you have, or can get hold of, a large enough container to fill with water? Then place the whole wheel/tyre in that and look for any bubbles.

Unless it is a fairly substantial leak I've never had any success with spraying water, soapy or not, onto a wheel/tyre.

Apologies if you have checked, but are you 100% there is nothing stuck in the tyre? e.g. a small nail, screw etc..

 

[sproutdreamer]

All sorted and thank for advice. I took it to my local Black Circles branch who first informed me that BC no longer does punture jobs. After a little persuasion of the financial kind he agreed to do it while I waited. He gave the rim a thorough wire brushing and did remove a lot of scale. Fitted anew valve and gave both rims a lavish coating of rubber based seating compound. All rebalanced in about 10 minutes.

The tyre fitter said they do a lot of alloy rim fettling but steel rims give few problems.

[Stevie J]

When I first got my 1999 1.0 CDX (in 2011 that was), I had issues with the tyres going down, and not just on one wheel either. The CDX and T spirit Mk1 Yaris used the same type of alloy wheels from the start, in 1999 up to late in the Mk1 run, and these tended to corrode and allow leaks round the rims. as the wheels on my CDX were quite corroded, I chose to replace the wheels entirely with new alloys, but it sounds like your wheels were the same type as the ones I had. In which case what you had done would likely sort the issue on the wheel that was losing pressure, but other wheels could well cause the same issues if they are also corroded. The picture was of my Yaris taken back in 2011, showing the type of wheel that I had problems with. Now I own a Mk2 and it has steel wheels - much less problem with them losing pressure - just not as nice to look at.

[sproutdreamer]

Thanks for the picture-yes those are like my wheels. I will have to keep a lookout for the other wheels.

When fitting the space saver wheel, the wheel nuts for the alloy wheels do not sit properly into the small recess on the steel space saver rim. Fortunately I have some steel wheel nut that I carry for my Avensis space saver wheel and they fit the steel rims securely. There is a little chamfer on the end of the alloy wheel nut but that does not fit into the recess to centralise the stud in the rim.