yeah, good point. I had no extender on the Michelin -- just using a normal box rim. My race wheels have screw-on extenders on them, valve locked open. Could be that it leaks a little air from that.

Although ... I will say that on my Zipp disc, with the valve being closed, I would still need to pump the next day

But not a scientific experiment at all!

Valve extenders and an open valve do not leak.

yes, sometimes they do. I've put them under water and watched the bubbles.

I have sold thousands of bikes and have never seen a leak like that.

If you have screw on extenders where the original valve is left open, then it's not the seal between the extender and the valve head that's leaking...it's the valve head itself. If you removed the screw on extender, and put the tube you are referencing under water, you would see the exact same bubbles.

If you have removable core extenders, and the seal between the extender and the valve stem, or the seal between the extender and the core tip is not sealed air tight, then yes it is possible to have a leak coming from the extender.

When I have commuted on a bike which had latex tubes, I'd typically pump them up to like 115 or so in the am, right before heading out. This would leave them roughly around 100-ish for the ride back home.

I'd rather them be a bit too high for the trip in (subject to tire/tube max PSI guidelines), than be too soft for the ride home.
YMMV.

You could also bring a pump to work and top them off again before departing after.

---

float , hammer , and jog

Right, this was with the extender taken off. The tire had gone flat overnight, I figured there was a small hole. So I pumped and put in water. It was leaking from the valve. BUT it had a small hole also

Out of curiosity I tried the front also. It was leaking very slowly also. Like a little bubble every second or 2

These were Vittoria. I tried a 3rd and it was ok

I'm sorry...did you say glass based chip seal?!?!? Is this really a thing? Chip seal alone is the bane of the cyclists lives around here where most roads outside of a city or a village that are not state highways (read that as 80%) get this wonderful "pavement life extension technique".

Yep. My neighborhood got it, and there was a huge increase in flat tires and complaints on Nextdoor for the 1st month or so before the loose fines settled in/rinsed away. I got a gnarly shard in my foot getting the mail barefoot. It's supposed to be tumbled, but apparently some pieces get missed. It has since made a nice, smooth surface, but the early days were awful. Here's a little more infohttps:http://www.pca.state.mn.us/...glass-road-aggregate[/url]