Re: Changing wheels
It's amazing what a bit of focus does:
The grease fixed the problem - I'm surprised at the magnitude of the change, so thanks Steve.
Secondly, I crawled under the car with the jack, and determined, that as you say, the seam takes the load - but only in the front!
The rear jacking point is slightly inboard of the seam, and is a plate with a hole in it into which the "lips" around the slot in the jack fit. I suppose it would be ok to use the seam instead, although you have to do this about 50mm in front of the jacking point arrow.
I'll go ahead with the hockey puck or similar idea, at least so I can use it on the trolley jack, but the grease means that it's not as urgent for roadside problems now.
2014 JGC Overland Cherry Red Off Road Adventure Package, ARB colour coded bar, 265/65/18 BFG's