Brakes sometimes act strangely (Kick back at full stop)

[DrunkenNinja]

I have a E53 2004 3.0d Sport with 19" rims and sometimes when I hit the brakes (Especially when gently) In traffic or traffic lights I get this kick back...

It seems to only happen when coming to a complete stop, it's weird cause after such a gentle approach suddenly the the car rears backward sharply, if I hit the brake more aggresively the x5 jolts forward as normal sometimes I find myself doing this just to avoid the horrible kick back...

I must admit my tyres are severly worn due to the seller not changing the tyres before selling me the car and will be changing them in the next couple of days could this be the reason?

Many thanks for any input...