Download RotWheel: automatic rotation and steering for wheels.  


This script moves and steers wheels according to their translation.


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 in text editor for all options.