[Closed] UST ready tyre on ust rim - why does it not stay inflated ?

Bad valve?

Have you tried checking for leaks with washing up liquid & water ?

porous sidewalls...

Unlikely to be the valve as it was on the last (ust) tyre and caused no problem. Porous sidewalls I thought should be ok with the sealant? And I am not sure abut the washing up liquid ? would I not see sealant pouring out of a larger leak ? thanks all for your input ....

Have been sold the tyre with the reassurance that it'll work on ust rims.

Is the tyre marked with a UST logo? If it is it should work even without sealant on a UST rim. If there is not a UST logo then it is not a UST tyre.

pop some washing up liquid in some water and brush it on the tyre, what you will properly see is a air leak where the washing up liquid bubbles up. If the leak was that big you would see the sealant.

try the fairy and see how you get on.

Bring it in A and we will take a look over it. Mine are working superbly.

There is always a slim chance it is faulty.

If you didn't use soapy water or something else to mount it then I doubt it's properly located on the rim

I'd never mount anything without the correct lubricant 😐

There was a good amount of latex on the rim when the old one was taken off, it wasn't wiped dry before the new one was put on. Plenty of lube plus extra jizz in the new tyre....

On the up side, its only flat at the bottom where its on the floor.... not all the way round.....

sounds like a non UST tyre - save yourself some time and use only ust kit. When fitting a UST give it a good thump all the way around this helps push it out and seat. Maxxis very good UST tyres. I only use them now.

Take the tyre off and scrub it inside with soapy water. The mould release agent stops the latex wetting the rubber and doing it's job properly. Doing this makes tubeless ready tyres stay up quicker.. but as above, if it's UST then it should stay up by itself.

Thanks to all for the advice!

Assuming there are no obvious large leaks, sounds like air is oozing out the sidewalls.

If it holds air for long enough to do so, go for a pedal. A 10 min ride should whizz the jizz round the inside of the tyre and seal all the gaps up.

If it won't be rideable, brush soapy water over the outside, pump it up and check nothing is coming out at the bead. If that's OK do the Stan's Shake - basically hold the wheel horizontally and swirl it about so the latex coats the sidewall, flip it over and do same to other side, repeat until it stays up. You should see the air leaks as bubbles or white ooze on the outside of the tyre. If you can get it to a point it holds enough air to ride, then go for a 10 min spin and should sort it out.

(EDIT - if it's "tubeless ready" - eg Bonty or Specialised 2bliss it will need sealant; normal UST ones don't. IME once it's set up it should be grand either way.)

Thanks Stu... lets see how it goes....

If you didn't use soapy water or something else to mount it then I doubt it's properly located on the rim

Rubbish, I never use soapy water.

Most likely is porous sidewalls, I'd echo Stu's advice and go for a ride if you can, if not give it a good shake. IMO there's no need to scrub the inside of the tyre and what not.

As for UST vs tubeless ready, UST are bloody heavy, I'd always choose tubeless ready, they shouldn't be any more faff than UST, sounds like you've been unlucky!

Given it a good razz at GT today and all seems fine. TL ready have light sidewalls and there were few burps... otherwise all fine.

@TBC.. all good thanks. Working well...

What rims are you using ? - I've had a couple of XM819 UST rims fail due to cracking of the weld (starts at the valve hole, and then spreads along the rest of the weld; air leaks out into the rim's "core" and then out through the spoke holes).

I've had similar issues but it was the valve. The core was getting bunged with dry sealant and stopping it from closing properly.