Yippee, I can go out and play with the "real" 4x4S in the snow and maybe rescue another Land Rover 
For those of you wanting to buy tyres, Tyremen in Yorkshire currently have stocks suitable for X5s, Camskills have nothing and cannot give an expected date of delivery - prices are a bit up on last year due to demand I expect and rising fuel prices. Tyremen have a price match promise if you find cheaper tyres in stock any where else. They delivered within 24 hours of the order, no hassle. the 18" tyre size recommended by BMW is 255/55R18.
Here is a useful linky showing all the different BMW styles and other useful stuff, offsets and part numbers etc. I'm now less confused about BMW wheels!!!
http://www.kalach.easynet.be/
My style 56 wheels with almost-new 17" Vredies (also Wintrac Extremes) are going on ebay if no interest in a day or so.....see the For Sale forum - they will fit all E53 X5s except the 4.8.