Stuffed would be when you fit the biggest rim/tire you possibly can into the wheel well. A proper setup would allow you to still rotate or turn your rims/tires at full flex.
---------- Post added at 04:55 PM ---------- Previous post was at 04:51 PM ----------
Most of the vehicles I have owned get 1" of lift per 1" increase in tire diameter. However, it does vary from vehicle to vehicle. If I lift my Yukon, it will be more like 2" of lift per 1" increase in tire diameter (damn narrow wheel well openings!).