Okay, well then I would suggest an upgrade to 266mm disks, these will fit under standard 14" steel wheels. There are three types, you will need the calipers, carriers and disks, though most will bold straight on, some may require a small amount of modification (a small part needs to be grinded off) you can find these items on:
1. Some 306 XSis, most 306 estates, xsara estates, some xsara VTS's' and VTR's, Citroen berlingo TD, pug partner TD.
2. C2, xsara, picasso, 206, 307 and partner van
3. 206 gti (not 180) & 206 CCs
If you are hunting some down, be sure that they aren't larger 283mm disks found on 206 GTI-180, 306 GTI-6, as these WONT fit under standard wheels.
This conversion is MUCH MUCH better than changing anything on the rear of the car. Upgrade to braided hoses too while you have the brakes off, but standard servo is fine with this conversion, although you may notice slightly more pedal travel.