what sort of jag?chris said:a spacesaver (mind that you have to get a 17" one to clear the brakes!) from a jag (much cheaper).
X_Type is 5x108 isn't it?
mostly what i see on ebay are 115/85/R18 (which is a close match - about 2.5% out)
are XJS, XJ6, XJ12, XK8 all 5x120.65 and is that close enough to fit?