Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing slow tyre pressure loss

one of my wire wheels loses all pressure over a few days. How fast varies. Sometimes after a drive it stays good for a couple of days, other times it deflates soon after. So driving affects it. Tyre good for many hours driving no problem.
What are your guesses? valve, tyre seal, wires themselves? Can't see any puncture evidence.

I would start with the valve - cheapest to fix and easy to diagnose with a dilute solution of washing up liquid smeared over the valve end.

Assuming you have tubeless tyres fitted without tubes it could be that the fitter damaged the sealant that is used on the spoke ends in the well of the wheel.

Or, it could be a standard slow puncture - wheel off and look for a leak in a large bucket of water (the plastic skips sold for gardening are good for a wheel rim to be rotated through).

You could always take it to a good tyre fitter.

Hi Parisa,
I had a similar problem and after checking for leaks around the wires with nothing evident it turned out to be just a tightening of the valve itself, hope it's that simple for you.

Regards

You can leave the wheel on the car and try this;
use soapy water and a paint brush to wet the spokes where they come out of the rim. One of mine had gradual pressure loss and the soapy water showed the air coming out from at least four spokes!
Easy to do and you will find where the issue is

Had this on the Roadster.

Ended up taking the wheel back to MWS to be re-sealed. I was told that it is not uncommon for clumsy tire fitters to damage the sealant strip.

Down side: it is an overnight process, the sealant has to be removed, the rim cleaned and then resealed. The sealant has to cure overnight.

I had a slow pressure loss on three tyres earlier in the year . It turned out that the retaining nut on the valve on my tubeless wire wheels had become very slightly undone (not unheard of apparently). This means that the internal sealing ring on the valve (located internally) is no longer pulled tight against the inner surface of the rim to provide an air-tight seal. After confirming this was the source of the leak with a weak soap solution all that was needed was to slightly tighten the retaining nut (external at the bottom of the valve adjacent to rim) and all was well and has been since (about 6 months) .

Hope this is the easy fix for you too.

If the above comments don't work try taking the wheel off and putting dilute washing up liquid where the tyre meets the rim.

I had a problem where the MWS rim stickers had been trapped between the tyre and rim

thx for the replies.
i'll try the soap. i knew of this method but didn't think it would work on a slow leak taking several days.
It's the original wheel & tyre, which was fine for 3 yrs. so i'm hoping that a valve will be the quick fix...

The valve can leak if the temperature drops, especially in winter.