Passwords for Challenge mode: Stock difficulty
Lightening = L
ATV, looks like an X = X
Wheel = W
Helmet = H
Up Arrow = Up
Finished level 1 L L X W L
Finished level 2 W H W H H
Finished level 3 + New ATV H Up Up Up X
Finished level 4 X L W L W
Finished level 5 L W Up H Up
Finished level 6 + New ATV W Up L X L
Finished level 7 H X Up L H
Finished level 8 + Pro Mode and ATV X W L W X