When it’s bone dry – what’s that all about then?
Seems to hold pressure really well, only 2-3psi drop in the last 3 weeks so doubt it’s coming through the side walls but if it’s stayed still in the garage for a couple of days there’s water on the tyres.
Seems like witch craft to me!

It’s sealant. There’s been a couple of threads on this recently. I have a theory that it’s more prevalent in warmer temperatures.

It’s the water based chemicals that make up a constituent fluid element of the sealant, it leaks through the casing of the tyre wall and beads on the surface, if you pop your tyre off the bead you will most likely find the usual stans fluid oddly shaped rubbery sealant gremlin rolling around the inner tyre.

@scotroutes – i actually find it more prevalent when its cold. When its warm it probably evaporates off before you notice.

I started a similar thread recently.

http://singletrackworld.com/forum/topic/my-tyres-are-bleeding

mine have just started this in the past few weeks, so ties in with warmer weather idea. Only on on tyre, though, Nobby Nic on back, front one same age (4 months old) and none coming through. Topped sealant up the other night, 3 months after installation, not sure if it needed it, but no harm squirting another 1/3 cup of Stans through the valve I reckoned.

I’m not sure about the warm weather hypothesis, as I installed a couple of new Specialized tyres in November and one of them (a Fast Trak) oozed and bubbled out of the sidewalls throughout winter. There was negligible air loss and the bike was kept in an unheated brick outhouse.

Porous sidewalls is my bet. I’ve only ever had this happen to me with thinner carcass tyres. They do seal up eventually but some take longer than others.

Try Orange Seal, it seems better all round (to me) than Stans plus no weeping sidewalls on Schwalbe tyres!