This script moves and steers wheels according to their translation.
Documentation
Go to User Preferences panel -> Animation section and enable the RotWheel
item.
Start addon in tools panel of 3d view (left pane).
Name your wheel or sphere objects 'wheel' or 'wheelFT' (wheelFT for added
steering) and key them in location only.
Wheels must not have any key in their rotY ipo channel.
See addon animation_rotwheel.py in text editor for all options.