I sloped out of work a little early, and headed out to get the new tyres fitted to the van. I was just up the road when there was a lot of noise coming from the back, so I was slowing down to pull over when I saw the wheel nuts fling off the rear wheel in the mirror. I carefully stopped off the road, and went back to look for the wheel nuts. I found 3, and put them back on, and went back to look again, and found another one. At this point the police showed up. 2 cars. Apparently somebody had called to say I was wandering around looking for something. I gave up looking for the last nut, and just did the 4 I had up really tight and headed over to get the new tyres fitted. They didn't have a spare that would fit, so I carefully drove home, then put on one of the stock wheel nuts. Obviously I'm not driving with my usual wild abandon, but the new Geolandar tyres seem quiet and well mannered, which is what Stephan said he's seen with them on his Syncro.
I'll order a whole new set of wheel nuts tomorrow.