Perhaps I didn't explain properly in my original post
Isuzu make three specs in their MU-X model. The base (which I have bought) has 17" wheels, the mid 18" and the top 20".
I up-graded (mainly because they had Bridgestone tyres, as opposed to Dunlop), but all three specs are the same car, same engine, but differing slightly in seating aerials, and electrical refinements.
I hope this clarifies the matter..