Unknown steel wheels

[1932 plymouth pb sedan]

Trying to identify 4 old steel wheels for a friend and I have never seen anything like them before.

The wheels are 18" with 4.00-18 Goodyear tires on them, look to have a 3 7/8" hub size, 6 locating pins, must have had a spinner to keep it mounted, they have a rather rough paint job in silver, look to have originally be painted yellow, the owner's grandfather had them in a barn for at least 60 years, he was a Harley enthusiast and I thought maybe for a sidecar, that would not make sense being 4 matching wheels and tires. Perhaps speedster wheels? Any help would be appreciated, it has me stumped.  

[keiser31]

Looks like something off an airplane.

[intimeold]

The 400 x 18 was a common size on vintage motorcycles. And that thread pattern was also used on motorcycles, usually in the 1930's and 1940's; but that rim is not like anything I have seen on a motorcycle or sidecar.

 

The mounting bolt diameter is not like any sidecar that I have ever seen. 

 

In saying that; it could possibly been used on a custom cycle-car or 3-wheeler. but not a known manufacturer that I have ever seen. 

[Layden B]

Agricultural? Narrow tires to go between rows of crops??

[28 Chrysler]

26 minutes ago, Layden B said:

Agricultural? Narrow tires to go between rows of crops??

I was thinking tractor or road equipment.

The wheels seam to heavy for aircraft with  only a 4 inch tire. 

[Larry Schramm]

It speaks truck to me, like for a rear dually truck.

[sagefinds]

I'm guessing military,either motorcycle,wounded person cart,or small artillery piece.

[3macboys]

Just trying to break down what appears to be known based on the original description and the pictures

 

2 piece steel wheel - doesn't appear to be a split rim 

 

18 inch with 3 7/8" hub

 

Appear to have had the Tremclad silver paint job while still mounted

 

Hex cap of some sort based on the paint outlines

 

Inside mounted flush would appear not to have had brakes based on the narrow band of rim not painted silver 

 

With @sagefinds response as I'm typing this - perhaps trailer is another option

 

[1932 plymouth pb sedan]

[1932 plymouth pb sedan]

Thanks for all the leads and insight, probably they were WW2 utility hand cart wheels.

[1932 plymouth pb sedan]

Come to find out that her grandfather had a couple of old wagons converted to haul maple sap out of the woods, if she finds a picture of the said wagons, I will post it. Thanks again for putting me on the right track.

[Layden B]

Model A Fords 1928-9 have 4.50 tires, these are 4.00 thus a smaller weight capacity than supporting a lighter car.

Of course steel construction eliminates aircraft.