fr tdi 17s

Hi all, I've just aquired an ex demo 56 reg 5dr TDI FR with the 17' alloys and 205/40/17 tyres, when I put it on full lock (left or right) there is a knock (just 1 either way) and it sounds like the wheels are rubbing the arches when doing 3 point turns etc. Surely this isn't right ...