Hey guys, I have found out you can use the minifgure style head piece inside of wheels to add some extra detail to some vehicles.
Sorry in advance for slightly blurry images I wasn't using the best camera and I have unsteady hands.
Style 1: IMG_20150207_124635620 by Railco1, on Flickr
Style 2: IMG_20150207_125438985 by Railco1, on Flickr
Hope you like these i think they are kind of cool, you do not need to include a 1x1 round plate but I did for a little color in the rim.
-RailCo
NOTE: You cannot do these with the new style wheels that clip in you can use them on the new ones that use an axle as shown.
[How you can use it for trains!]: http://www.eurobricks.com/forum/index.php?showtopic=105603