Tyre losing pressure but is brand new?

[electricfurnace]

Bit of an odd problem I'm having with my girlfriends '97 sportpack cooper.

Basically approx a month ago the rear passenger side tyre was down to 16psi all the time. Must be a slow puncture, I though, so we had a new tyre fitted.

Thing is, it's happening again even though its a new tyre!! Pressure goes down to 16psi after a couple of weeks!

Definately no puncture, any ideas what could be causing this?! All the other tyres are fine.

Thanks
Alex

[ljonez]

had the exact same problem on one of my sports pack alloys

turned out that where the balancing weight was clipped over the rim (in the inside of the wheel) it was pushing on the side wall and creating a leak

[boycie101]

check that tyre is sealed properly, we had same prob once again when new tyre was fitted, constantly lost pressure so took it back to tyre place + they removed the tyre, wire brushed the rim as was looking bit manky + put tyre back on + everything fine once the rim had been wire brushed down. tyre had not sealed properly cos rim had few corrosion bubbles