Quote:
For a static assembly (not taking into account suspension motion) and constant pressure of brake fluid, brake performance depends primarily on these items -
1. Caliper piston area
2. Pad friction material area
3. Coefficient of friction of pad material within a temperature range
4. Effective clamping diameter of the friction material
5. Type of disc material.
6. Temperatures of disc and pads.

If you use larger rims on the above setup, then brake performance will deteriorate. If you must use larger rim/tyres on your car, then use proportionally larger discs and calipers to maintain brake performance.

Also as rim/tyre size goes up, so does unsprung weight and the ability of the tyre rim comination to follow the road surface without skipping on bumps. Large/heavy rim tyre setups and small stock brakes are the cause of a lot of crashes in performance vehicles.

I have a spreadsheet with a bit of comparitive brake data that is a bit of a surprise.