How to make a side scroller dirtbike move across hills.

I am working on a side scroller game. There are hills and obstacles. The problem is, no matter what I try with rigid body's on the wheels, the entire gameobject, just the frame, whatever, It wont work. Either the wheels move without the body, or the body moves without the wheels, or every part spirals in different directions. all I want is for it to move across the screen.. being able to tilt like a dirt bike would going over hills.. if he goes off a ramp, he is in the rotation of this ... "/" then after a little air time it becomes this rotation "\" and lands becoming this rotation .-. How can I do this.. cause its been two days of trouble shooting and I finally have to get help.