I have just converted a couple of wheels with Mavic 719 rims to tubeless, using Stan's rim convertor thing. Tyres are Nobby Nic's UST.

The first one went up pretty sharpish and has stayed up for quiet a few rides, no problem. The second (different bike, long story) went up straight away but then within 24 hours is flat. Reflate then it goes flat again. There's no obvious bubbling or noise of air escaping anywhere – put my ear all round it.

Before I dive back in and start again (I'm out of solution now, so trying to avoid taking the tyre off again), anything simple I might have missed? I'm guessing not, but worth a try……

Could be leaking at the rim or from a join in the carcass of the tyre.

I've had Nic's and Raplh's do this – inflate it and then slowly turn the wheel with it lying horizontally both ways up.

Going for a ride is often enough but I've had them go flat again a week later – this has usually been down to a leak from where the sidewall of the tyre meets the treaded carcass. A quick pump up followed by turning the wheel in various axis has always sorted it.

Thanks nenija. I haven't actually ridden it yet so maybe will try that plus the horizontal turning will sort it.

Good answer – it didn't include starting again!

Cheers

UST

water over the inflated tyre to identify the air leak?

no reason to lose the latex solution when you take the tyre off either, i easily transfer the liquid from one tyre to the next with minimal spillage.

I had this regularly when swapping UST tyres about.

LBS advised:

Use muck off (or similar) to lubricate rim/tyre interface when inflating – also use of Co2 cartridge makes for better seal. Over inflate, up to as much as 50/60psi to ensure tyre bead clicks onto rim.

Use wheel milk or similar to help seal tyres, once inflated, role tyre round in the air (holding wheel level/horizontal) letting the sealant work its way around the tyre bead/where it joins the rim, the sealant I was told helps seal the tyre and make it airtight.

Having followed the above process each time I change tyres no more air loss. Hope this works for you. Also make sure Stans rim tape is flush and actually sticking to the rim all the way round, on my Stans flow rims I had to re do the tape after the first one developed an air bubble near the valve hole which leaked a slow amount of air over a few days.

I should add, once left for say 10mins at 60psi, I reduce back to normal pressures.

also check the tyres is on the rim evenly all the way round,you can find the side wall is trying to make the seal not the bead

Cheers