I was in a pinch to move my kettle (yes #4 red head) and the wheel keeps falling off, missing the hub cap. So I went to the garage and to found something to keep the wheel on the axle shaft. Could not find a retaining washer so I start looking in my parts bins and I find some left over fuel line the diameter is about 5/16.
I cut a piece 1/4 in length. So I take it out to the yard and try to push it onto the axle shaft, it works perfectly.
Pulled the kettle around go to go wheel has not come off.
Hope this helps you if you are missing your hub caps.
CD