Old 07-11-18, 04:51 PM
  #14  
robertorolfo
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Location: Queens, NY for now...
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Bikes: 82/82 Lotus Unique, 86 Lotus Legend, 89 Basso PR

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Originally Posted by leob1 View Post
Check that the tire bead and the rim bead are compatible. If the tire is designed for a hook bead, it will not work well with a non-hook bead rim, like the ones on you 1986 Lotus.
They stretched after being mounted for a while, and now the tire isn't seating well on the rim, letting the tube slip under the bead and KABLAM!
Lot's of good feedback here, and I'm really thinking this might be the case. I'd say I generally run at fairly low pressures (the 75-85 range), so that's probably why it hasn't happened more often, or since.

Originally Posted by zacster
The OP did say that the pump was wonky. So if he overinflated the tire and the tire/rim combo is a little loose, it could potentially blow off. Add to that that on July 1st the temps were like 100F here in NYC. The second blow out was probably caused by the first. I just had another thought on re-reading this. Did you damage the rim in any way recently? Any minor spills that you didn't give any thought to?
Good memory! July 1st was indeed very hot, and I thought that was part of the issue, but the second time was after the bike had been inside my GF's air-conditioned apartment for over 10 hours, after being inflated in my own, non-airconditioned apartment. So I don't think it was temperature related.

And I don't think it was drastically over-inflated. My pump gauge is unreliable, but I've never gone above 115 psi with it, and that night I didn't go above 105, while the tires are rated on the sidewall for 130.

And the tire itself seems to be in good condition, although I did notice that along the bead in some places the rubber has worn through to expose some threading (I think it's threading) underneath. And for the person that asked, yes, they are folding bead tires.

Rims and rim-tape also looked good, but every day brings a chance for some damage here in the big city, so nothing is 100% certain. I've been riding on a replacement tube since Monday, though, at around 75psi, and I haven't had an issue.

Also, just to mention again, both blown out tubes had long slits in them (around 8 inches long), so I'm pretty sure the tire was coming off the rim and letting the tube escape to blow itself up.


Originally Posted by leob1
Check that the tire bead and the rim bead are compatible. If the tire is designed for a hook bead, it will not work well with a non-hook bead rim, like the ones on you 1986 Lotus.
They stretched after being mounted for a while, and now the tire isn't seating well on the rim, letting the tube slip under the bead and KABLAM!
Forgive me for sounding noobish, but do they make folding bead tires designed for a non-hook bead rim? Am I asking too much of my vintage equipment?

Originally Posted by AnkleWork
Tires are macro systems governed by determinism (Newtonian mechanics).
Again, pardon my unenlightened question, but I thought the whole point of Quantum theory was to fill in those blanks where Newtonian mechanics come up short. Of course it isn't going to explain what is going on with my tire, but isn't it involved in everything on some level? I mean, my conclusion from my forays into this topic has always been that we really don't understand exactly what is going on in our universe, so...
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