Pause the game, hold Shift and enter one of the following codes:
Burnside level: 648W
School level: 648A
Warehouse level: 648D
Granny: 648S
Tony Hawk: 6488
10X score multiplier: 466WSS
10X score divider: SSW664
Special always full: AS86WA84
Perfect balance: 4AWD
Fat tires: S66S