I have recently bought a 98 Range Rover. I can't find anywhere in the manual how fast you can/should go in the Lo/Hi gear in 4wd. I drive through mountain passes frequently and although covered with snow can usually travel about 40-50mph in my 4wd Chevy PU.

What can I do in the Rover?

 

35 is recomended top speed in low range, however, unlike your chevy its a full time system, your always in 4wd, only real reason to switch to low would be for low speed manuvering, such as rock crawling or anything where a lot of torque is needed, as far as snow and hills go, high range should do you just fine