Wheel rattle

G'day all,
I own a 1982 BMW 320is, and the front right wheel (the wheel only, nothing conected to it) has a rattle when I grab it and shake it. It sounds like it could maybe be the king pin, but, then a lot of other parts would be moving too rather than just the wheel. I haven't had the chance to jack the car up and check it out, but i was wondering if anyone had any thoughts??

I need the car for auto-cross events this month and next, I really want to find out what this rattle is before my next event in two weeks time.

cheers