i was at a hardware store once and a man from England came up to me and said that you should go over 7.50x16 as anything larger will cause unnecessary wear on the wheel bearings and make it more likely to snap axles, i have even been told by a local man that he had a land rover with a Salisbury diff in the rear and he managed to snap the axle, i have 7.50x16 on my series 2a they are MRF brand made in India, i pay$230 for them they are the cheapest i can get that are non radial type, i will wear the front two but they are good on the rear i get about 4 to 5 years out of them.