15s are probably the optimum wheel size for the Mk1 non-wide arch (i.e. not 16v/Williams) Clio. I fitted 15s and 16s on my old 1.2 and the 15s were easily the best - slight rubbing, but it was lowered to the floor. 16s meant major rubbing, poor handling (not to be confused with grip) and poo acceleration/top speed.
On a 16v/Williams or a Mk2 Clio, 15" is a bit on the small side for an aftermarket wheelset - besides, the 16v and Willy look best on the original 15" wheels.