Checking Slime-tube pressure?

[peterb]

May be a silly question, but asking as a new Slime-tube user, is there a problem with checking tyre pressure (and adding more air) given that the Presta valve needs depressing when fitting the pump chuck? Is the Slime expelled, thus blocking the valve?

[Jdsk]

Previous discussion:
viewtopic.php?p=1792992#p1792992

Jonathan

[peterb]

Thanks Jonathan. I did search the forum but missed that. It's day to day pressure check I'm thinking about, not major changes. So far my experience - using the 'thumb test' - is that the pressure has dropped very little, if at all. Less than standard tubes, which often need topping up from week to week.

[rogerzilla]

Put the valve at 5 o'clock or 7 o'clock, wait 5-10 minutes, then attach your pump and check the pressure.

With butyl tubes, a typical road tyre only needs air every three weeks before it's lost enough to affect anything. Lower-pressure tyres can go longer than that.

[Brucey]

Thanks Jonathan. I did search the forum but missed that. It's day to day pressure check I'm thinking about, not major changes. So far my experience - using the 'thumb test' - is that the pressure has dropped very little, if at all. Less than standard tubes, which often need topping up from week to week.

pressure changes also vary with the size of the tube too. Since air will slowly diffuse through rubber (even if there isn't an actual hole) and slime inhibits this to some extent, it all makes sense.

[Audax67]

Put the valve at 5 o'clock or 7 o'clock, wait 5-10 minutes, then attach your pump and check the pressure.

Funny, the leaflet with the Slime tubes I use says 10 o'clock or 2 o'clock.

I expect mine to lose about a quarter to half a bar in a week so I simply connect the track pump and take it up to pressure. I never just check via the valve, since in doing so you let air out.

[rogerzilla]

10 or 2 o'clock doesn't work, as some stays in the valve stem. I've tried various permutations.