It looks like this Part has been superseded by LEGO Part 6014b Wheel 11 x 12 with Hole Notched for Wheels Holder Pin.
Click on a colored part below to see the Sets and MOCs that use part 6014a Wheel 11 x 12 with Hole Round for Wheels Holder Pin in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.
This part has been used by MOCs in the following colors but not officially released.
There are 3 Mold variations of part 6014a - Wheel 11 x 12 with Hole Round for Wheels Holder Pin in the database, in use between 1991 to 2013. See Molds and other related Parts.