Tyre Losing Pressure

[steve g]

My 2009 GSA front (EXP) did exactly the same. Had to top it up every week normally. Just had new tyres fitted - wait to see the outcome

 

[Rocky Mountaineer]

The front tyre on my 2009 1200 GS has been leaking since new, the mechanic noticed it when he did the 600mi service. Whenever it was left on the main stand it dropped to 1.7bar and this week, after being away for 3 weeks, it dropped to 1.2 bar. BMW checked it at 600mi service, again when it was in for a replacement seat (warrranty claim, faulty), and again when I was in to pick up the new gear (Streetguard 3).

Mechanic had another look at it again this morning, and discovered that there is a flat spot defect across the casting. Apparently not common, but it happens. It's been frustrating to have to keep checking / refilling your tyre on a new bike...hopefully sorted now.

Warranty rep said it could be due to hitting a pothole, as can happen with low profile tyres on BMW cars. Nope, haven't hit a pothole and the stock GS tyres can't really be classed as low profile. They've got the bike overnight, until they can get another wheel. They've loaned their F800GS to get me home (rather liked it, but still miss my bike).

Fingers crossed, but something to check for if you are losing front tyre pressure for no other reason.

Tyre now seems to be fixed, after a few trips up and down to Dundee (replaced wheel, then replaced valve). Pressure was stable back up the road, but the real test will be when it's been on it's main stand for a few days and that's unlikely given the current weather in the UK northeast.

 

[Owen Snell]

We did the whole Nitrogen discussion a few months ago - it is nonsense really. Just some pseudo-science invented by someone who thought they could make a fast buck.

It is used in aircraft tyres to reduce the risk of fire, but does not have to be Nitrogen, just any inert gas will do - and it is not more thermally stable, the pressure of all gases changes with temperature pV=nRT innit!!

The reason that Nitrogen used in tyres is more thermally stable is that it is from a controlled source (i.e. a bottle of gas) and so is dry. Dampness in the air converts to condensation in the tyre that then partially evaporates when the tyre is warm, causing a bigger variation in pressure than would normally be the case with dry gas.

 

[Fanum]

i want to fill mine with Nitrous Oxide...

just for a laugh.