realskiers

What Jim said.....    Good info to know.  Thanks Liam.

You're right about the Slant Six -- it has significantly thicker sidewalls than the paper thin SB-8, but certainly not bomb-proof.  I won't be going lower than 35psi with tubes, at least at my weight.   

I was reading last night about the need to top up the sealant every 4 months, presumably because the liquid is by then evaporating and becoming gummy and will no longer circulate to reach and seal a puncture.  But does the bead-rim seal also start to lose integrity and start leaking air? In other words, let's say I wasn't worried about punctures and didn't bother to top up the sealant.  Will the tire hold air for say, another year? Or two? (assuming I keep it pumped up, of course).

Basically, I have this unappealing thought that if I put a tire on and leave it on for two years, in which time I will have added about 200ml+ of sealant (if I follow the regular top-up recommendation), there will be an unholy mess of sticky 2-year-old glop all over the rim when I finally do take it off.  The alternative being that I have to strip the tire off every 4 months, clean it all out, then remount with fresh sealant.  I sure hope it just rinses clean with a garden hose. 

OTOH, if I can just mount it once, squirt some stuff in, and forget it for two or three years until I decide the tire needs replacing, then this is suddenly looking much more promising.