I always chuckle at my bro's Escalade on huge rims. Those brake rotors are so tiny for a vehicle this size, and with oversize rims.. looks funny.
By the way, rotors on regular x5 are bigger in diameter than most vehicles, large and small. In addition, the brake pads seem to be wider (judging from shiny part of the rotor).

That could explain stopping distance for x5 being shorter by ~30 feet compared to competition.

That reminds me. I got iDrive telling me my brake service is due. 1300 miles for fronts, 2500 for back. A bit weird how it works. A month ago, iDrive told me my fronts are due in 15K, rears due at 3K. Now the fronts "passed" the rears in a couple weeks time.