I have got an air leak between the rim and tyre, you can see small bubbles at the rim/tyre interface. It is enough for one tyre to go down 20 psi and another to go almost completely flat overnight. The rims are stans flow with tape and rim strip and the tyre are standard kevlar Kenda Nevegal. Both tyres are seated well into the rims and it looks like the bead is seated okay. I have used about 200ml of sealant into both tyres and i have rotated, left on side and gone for a short ride etc.

SO i am out of ideas, my next step was to take the tyre and rim strip off and put a couple of extra layers of tape on the rim. Probably electrical tape rather than the stans stuff, the aim would be to get a tighter fit between tyre and rim. Good idea? Also can i reuse the stans sealant that is in the tyres already?

cheers

200ml of sealant? I use around 60 at most. Just pump them up again and go for a ride see if that sorts it.

Of course you can reuse the sealant.

mrl – It shouldn't be necessary to add extra tape. The tape is for sealing the spoke holes.

Have they ever sealed? If so, what's changed since they did?

As both front and back have the problem it's sounds like an installation problem rather than rim or tyre problem.

Had you fitted tyres tubeless to these rims before? If you had, you need to give the wheel rims a really good clean with a brillo before fitting new tyres as you get a build up of latex around the edge which can stop a new tyre seating properly.

The same is also true of the tyres. If they've been fitted tubeless before, all latex residue needs removing from the bead.

Also did you shake and pour the Stans solution with the bottle inverted? If not you might have 200ml of fluid in but with insufficient of the sealant granules in it and loads still in the bottle.

How high have you pumped them up to? I've needed to pump mine up to 60psi before for them to eventually pop into place….

Your not by any chance getting confused with air leaking through the side walls as opposed to along the rim? If so you need to do the slosh the fluid around the inside of the tire and lie on its side for 30seconds technique and repeat this for both sides about 10times, or cover tire with soapy water and do this until no bubbles appear.

If it is definitely along by the rim, are the tires new? There could be holes in the tire along by the beed, I know I get alot of holes in my tires along there and sealant can only reach it if you do the sloshing technique as above… however sealant can only hold up to about 30psi anyway so you might need to patch the holes… hope this mumbling is of some use!

Kenda Nevegals take time to seal properly as the sidewalls are very porous. Persist for a while and eventually enough of the sealant will penetrate into the sidewall and you'll be fine.

I've just done Nevegal on a Flow. I had the same problem but after a couple of rides its sorted itself.

More tape can help if the rim strip isn't coming up to the rim bead – electrical tape has worked fine for me although the adhesive can supposedly be attacked over time by the ammonia in the Stan's milk.

Make sure you've used virtually neat washing up liquid around the bead to help the tyre seat properly.

The rims had been used with a tube only. I cleaned out the rims with brake cleaner and a bit of wire wool. The tyres are new (one had 3 rides and was cleaned first). Pumped them up to 40 psi, i am pretty sure they are seated okay, i will try 60 though.
The bubbles are forming at the very base of the tyre where it joins the rim, I guess it could be the side wall rather the join but only the very base along the bead.

I will go for a ride and hope it sorts itself out!

Just ride it more, it'll most likely sort itself, had the same with nevegals and small blocks and never had one that won't seal after a little patience.