Looks like either a car file or another file within the game hasn't install right, the game is looking for a wheel thats probably built into the car file..
I would re-install the lot again m8, I know it takes a little time but could be quicker than trying to figure all the problems out, re-install making sure each file installs into the default directory.
Maybe back up the folder that holds the tracks this will save a little time then just copy back over, make sure you install all the ukdirt updates and patches etc in order, then install the banger offline skinpacks to make sure your working ok.
Hope thats of some help