We've just learned that my 1957 XK140 should have metal tire valve caps rather than the rubber ones that are on it. Could someone tell me, please, is it acceptable to use the standard metal tire valve caps that are readily available, or is a 1957 XK140 supposed to have something special? We do intend to show the car so we want to get the right parts. Thanks!

Janet Iagnemmo (1957XK140 DHC MC)