Take a look around some of the other forums there's loads of advice around. IMHO for that amount of off/on roading then a set of BFG AT's is a good choice. But it does depend on the type of offroading you do. I have BFG Trac Edges fitted to the 90 and the Disco which I consider to be the best compromise between a Mud and Road tyre. But they don't make them anymore. So when it's time to change I shall take a good look around but I am considering
Cooper Tyres
HTH
Ivan
