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I have Avon Storms on tha Falco running the original wheels, last rear tyre lost approx 10psi a fortnight whether it was being ridden or not so when i renewed the rear with another avon storm i made sure the guy put in a new valve and cleaned the rim but i still have the same problem. A mate of mine said he'd heard this was a common aprilia fault, is he right or talking out of that which he should be sitting on?

danthewhippet wrote:A mate of mine said he'd heard this was a common aprilia fault, is he right or talking out of that which he should be sitting on?

Pure Bollox (though sealing the valve to the rim with OZ wheels can be more difficult than with other rims)

Only if the tyre fitter is a muppet - aprilia / Ducati many other European makes use a different size valve in their wheels compared to the more common Japanese machines

I agree with Pete and Andy.

I got a right angle valve put on my rear Oz and it works fine, the front was a pain and still leaks a bit (I'm confident it's the valve) different fitters same valves.

IIRC old Kawasaki's had an issue with porous wheels, but never heard of this with Aprilia

My local fitter says That the ape wheels are the best finished that he works on ... Can't think that they would do that to make a more basic cock up ... I had a problem last winter and not the sort the doctor could fix so went to him and first we fixed a puncture (big hawthorn) then tried checking the seal and it was the valve which had corroded on the inside from all the salt slush crap

Porous wheels !
That dude gotta be smokin some special weed !
The obvious has already been said....
wrong size valve, oxidisation around valve seat, maybe damage/oxidisaton in the well that the sidewall bead sits in preventing a good seal.
It is not unheard of for tyre fitters to file out the valve hole in order to get the wrong size valve to fit.
Get the tyre off and have a good look.
I spilled across 3 lanes of M5 after a blowout, this is not on my Things to repeat list

Sorry. to clarify, he wasn't suggesting porous wheels merely poor fit. I've been all over the rim and valve with gas leak detection fluid and never found a peep . The odd thing is that it's never been lower than approx 30psi and that's after sitting under a cover all winter. It's an inconvenience more than anything else as i regularly check the pressures anyway and it only takes a minute to top it up. Maybe chuck some tyreweld in it if starts to annoy me .

Change the valve

Check the valve core is done up tightly first

and remember loss of pressure can be normal such as weather / temp changes etc and by GAS detection Fluid do you mean soapy water?

To echo what D-Rider said, get a valve core key.
if the tyre is down, remove the core, look for crap on the threads or damged treads.
I have a 4 way key with a thread chaser on it, cost 99p plus vat from a farm supply place

flatlander wrote:and remember loss of pressure can be normal such as weather / temp changes etc and by GAS detection Fluid do you mean soapy water?

Na mate, LDF, different gear. We're not allowed to use soapy water

leaky bladder but that's prolly just my age

Tyreweld?? I hope you're joking! :-p

My guess would be an ill-seating valve core as well. Could be the fitter's not used enough tyre soap and the tyre's bead has not quite settled properly on the rim?

Pourous rims aren't unheard of, especially on old magnesium alloy wheels, but modern stuff shouldn't suffer from that.

Remove the valve core, make sure everything is clean there, check the thread for damage, re-fit, re-inflate the tyre and see what happens. You could use a tyre sealant (NOT tyre weld), either Puncturesafe or Ultraseal (same thing). Avoid cheaper sealants as they're cheap for a reason. If it's a slow puncture this should fix it. If it's the valve core it won't.