cool cheers, it's got virtually new tyres on the rear at the minute, should they be left at the back for a while?

Hi this is my first post, i've been running a 2002 GS 2.5 station wagon (it's on 93k)for about 6 weeks and must say i quite like it being my first ever 4x4 and auto all at the same time, but there seems to be a wheel bearing like drone coming from the rear, no particular side so far as i can...