Originally Posted by triggermortis
I have tubeless on my MTB and never have any problem inflating new tyres. I use a track pump and keep the valve at the 12 o'clock position and press the tyre towards the rim with my hand thats not operating the pump. That forces the tyre to go towards the seating position on the rim. Usually the tyre stats popping (literally - it makes a popping noise) into place and I pump it until its fully inflated. Soapy water helps to seat the tyre and see any leaks.
Once it has been inflated for 5 minutes, I deflate it, remove the valve core and pour in the sealant (I use Stans) refit the core and re-inflate - keeping the tyre upright and the valve at 12 o'clock. Then I give it a good spin to move the sealant all around.
@ Eamonnator - If you're close to NCD, I'm working lates all week and so have every morning free if you want a second pair of hands to try and get them fitted. I've never tried road wheels, but it can't be impossible
Just to add a bit on top of what triggermortis has said above (and adding the disclaimer that I'm coming to this from an MTB point of view)
, if you're having a lot of difficulty getting a tyre to inflate/seat onto the rim, be mindful of the particular tyre model that you're trying to fit. I experienced this with a Schwable Nobbly Nic tyre, of which I hadn't realised was the super-light pacestar (or whatever it is) rubber compound version, which requires the inside of the tyre to be treated with an additional liquid/sealant to close up the holes in the rubber itself before you try seating/adding tubless sealant. Took an absolute age to seat, a visit to a shop to seat, and then still continued to deflate. I could see sealant bubbling through the carcass sidewalls all over the place like there was a thousand and one pinpricks. I reckon I used up about x3 the amount of sealant I needed to, and the whole thing dragged over several days until finally the tyre held pressure overnight. By contrast, I've fitted Maxxis High-Roller/High-Roller II/Minion DHF tyres on separate bikes and never once had an issue with seating, getting that lovely 'pop' sound on first attempt every time. I'm not trying to single out Schawble tyres; my point is that the tyre model/variant itself may require additional steps that aren't immediately obvious.
Two other points to note:
Tubeless sealant - from what I've read through various discussion boards on the matter - does not seem to like CO2 very well, in that the sealant is at risk of being dried out. How quickly I couldn't tell you but that seemed to be a common opinion held. For seating, a decent track-pump should see you right. Doesn't even need to be expensive. I use a Lidl track-pump. Or you can get track-pumps with compression chambers for high-volume air through-put. You can also get the cylinders separate from the pump if you already have a good pump; just fill up the compression cylinder with the pump, connect pump to tyre valve, and away you go.
Valve stems & sealant top-up
If you're fed up of the whole popping of the tyre off the bead to pour in more sealant and then repeat the whole re-seating of tyre whilst avoiding a mess, and you aren't prepared to use the (imo) crazy syringe-through-the-tyre method; I use Milkit
valve stems. They're intended to use with a syringe/plunger setup but you insert (or remove) sealant by going through the valve stems themselves. The stems have rubber inserts that prevent air escaping whilst the valve cores are removed, allowing you to seat the tyre with no sealant present, then fill with required amount of sealant via the plunger/syringe, insert valve core/inflate/job done.