The Leon wheels I have are fitted with Bridgestones. Have to say that these give grip straight out of the box, unlike the Goodyears I had on the front before, super tyres, but gave best grip after 1000 miles or so.
Mediaman, you may want to check a thread just started about Dunlops, just to make sure yours aren't affected in the same way as another member.
Dan's Leon with18" wheels look superb and it does suit his car much better than the 17s would. Ace car all round! I quite like my Altea with the Leon 17s, I suppose its different.