E39 M5 alloys leaking?

[FurtiveFreddy]

A friend with a 2001 M5 claims his alloys (standard factories) are the cause for his tyres to lose pressure.

I'm assuming they weren't split rims (?) so is this going to be leaking around the bead or the valve? Will a proper refurbish be able to fix the problem?

[Depthhoar]

Style 65 BMW OE original wheels are not split rims.

My tyres lose no (nil) pressure but the rims are in great condition so either your mate's wheels are corroding near the bead contact area (often difficult to detect visually), or it's something else.

The valve is worth checking. I replaced some valves on my second set of Style 65s the other year - found the old ones to be quite perished and would have started leaking at some point soon had I not changed them. (The correct tyre valve size is TR412; some tyre fitters put on the longer versions which flex and mark/damage the rim.)

Don't rule out a slow puncture either.

A good refurb should sort any corrosion issues on critical wheel/tyre mating surfaces. (But not all refurbs are created equally! You do seem to get what you pay for.)