i understand why kids nick dustys, and to be fair, theres worse they could be doing, like keying!! not that there excused!! mine went missing 3 days after i had the car!
so i got myslef some of those richbrook anti theft spinning caps from halfords, not bad actually and they look ok as theyre black and silver so kinda match the car! though you do run the risk of the theivesgetting frustrated by it not unscrewing then they just yank at it til they wreck the valve!
one tip if you get them, keep the little tool for removing them in your car at all times, otherwise you feel a right idiot when u drive all the way to the petrol station to do you tyre pressures!!