@DaveD. Sorry if you've said it before and I missed it but is your van 2 or 4 WD? I seem to recall that you've already mentioned being on 18s.All Season tyres have improved a great deal over the years and only a very small number of people need All Terrain tyres, I cross muddy fields regularly but the AS tyres are good enough at that but don't compromise safety for the 90% of the time that I'm on tarmac.