I have been doing some working on braking energies, and have hit a bit of confusion with regards to the kinetic energy of the wheels and tyres. Obviously, the kinetic energy of the moving car itself follows the old rule of 1/2mv2. For a 1000kg car at 30ms that's then 450kJ. I have then calculated the kinetic energy of a 12kg wheel/tyre with a rolling diameter of .575m, assuming the 'centre of mass' to be at 75% of the rolling radius as 57kJ. (30ms = 105 rad/s) This seems substantial addition to the total kinetic energy over four wheels. Now, assuming I have not made a big mistake (I may well have done), should that 228kJ be added to the 450kJ of the moving vehicle, giving me a total of 678kJ of energy that must be removed from the car to bring it to a standstill? Or is it somehow absorbed into the 450kJ?