HELP! with group problem

im making a car simulator and my wheels have automatically grouped to the car, how do i un-group them so that i can modify them in object mode?:spin::spin::spin:
http://img341.imageshack.us/img341/6963/workscreenshot2.jpg
http://img28.imageshack.us/img28/248/workscreenshot3.jpg

select the wheels and press ‘p’ -> ‘selected’

thanks its working now