I dont see why not - however you would also need to have very expensive, and
very quick wearing low profile tyres with them. Maybe Yoko A500's or
similar.

This would give the car fanstasic grip in the dry but when it comes to the
winter, the car would not get up a slight incline hill with a light dusting
of snow or ice without slipping more than banaman on a banana skin. But you
could always keep the current wheels for winter driving.

The other problem would be the clearance - You might have to stiffen the
suspension depending on how close the tyre comes to the frame. If your son
has heavy mates in the back or decides to carry a couple of bags of sand
about then those arches might start rubbing...especially round tight bends.

All this in turn would put massive pressure on the suspension, making it
more likely to be needed to be replaced in the near future and it will also
give anybody with piles a very uncomfortamble ride. every small pothole and
raised manhole will fell like a 20ft drop. And those speed humps will be a
constant problem.

If the wheels are for shows then yet - they will fit but I would not
reccomend fitting them without doing the other stuff - else you will need to
buy your son a new car again very soon...

Dom

its going to make it a theft magnet, but tirerack.com should have all
the fitment info.

As the other guy says, yes, they'll go with the right tyres on.  The ride
will deteriorate.  You may find the wheels catch the wheelarches, probably
through width I'd guess the standard wheels are 6J, the 18s might be 7J,
that's an extra inch wider and with the correct offset most of this will sit
in the wheelarch).

But one will be paying a lot of cash for the combination now and various
bits and pieces will wear out much sooner.

From an aesthetics perspective, it'll look naff with standard wheels behind
those big wheels.  It won't look finished.  It'll look like somebody thought
big rims were "cool" but didn't think about the consequences.

We've not even begun to consider the unsprung mass.  Most aftermarket wheels
are heavy.  If the TSW Kayalamas are heavy, you'll stunt acceleration and
braking too.  Not to mention in the wet the car will be much snappier, i.e.
when approaching the limit of adhesion it'll tend to go from "driving" to
"skidding" very quickly.  On standard wheels you get much more warning.

If it were my lad, I'd insist if he wants stupid big bling wheels, he buys
his own car - but that is just me heh.