hi gaz, ive always run 235x45x17, its easy to get a high load index in this size but with et37 you couldnt have your van really low... pretty sure you wouldnt want it really low anyway but worth a mention... im running -60ish and never rubbed, but ive been very aware as they would with lots of weight in the rear....
others will say 225x50x17, rolling diamiter wise there very little in it 4mm, but think you could get the wheel arch over the tyre with this size, just,T:
ps whats that avitar, cant make it out...