Technical 50 Chevy rims won't rotate on 54 Chevy, why?

I have a pair of 1950 Chevy car rims, (Center section is welded into a modern hoop). When I put them on my 54 Chevy sedan with stock drum brakes, the wheel won't rotate.
I can't find anywhere that its rubbing. I thought, maybe the center is smaller on the 50 rim and putting odd pressure on the rotating ***embly somehow. So I tried a small spacer. Same problem.
Any idea's why these wheels don't work on my 54 Sedan?
EDIT: This is on the front. I haven't tried the rear yet. When installed I ran my hand around the inside of the rim trying to find where it might be hanging up, but didn't find anything.
(pic below is when I had it on an AD Chevy truck)

 

Front - hub and drum spin, so if the wheel tightens down and locks up, look at the backside and see what the wheel/tire is touching.
Rear - Axle and drum spin, so the wheel/tire must be contacting something behind (Spring?)
I doubt the wheel center is flexing the area where it mounts when the lugs are tight, causing the brakes to bind. It's almost certainly wheel offset causing it to hit something.

 

Seems if the wheel isn't rubbing on something then it may be contorting the drum, enough to cause it to bind up the brakes or contact with the backing plate.

 

Did you jack the tire/wheel up off the ground?
Pictures please

 

I shook my Eight Ball and it said….
They don’t fit.

 

Put the wheel on finger tight. See if it spins. Tighten it in steps until it rubs and listen for the noise. As others have said I would suspect it to be outside rather than inside the drum. If it works on one Chevy it generally works on others.

 

I shook it again and it said….
Release the parking brake.

 

Front or rear?

 

Was going to go there but thought I’d ask front or rear first.

 

I ran in to a similar problem years ago with my 54, I had some rims I put on I don't recall what they were from .But they fit fine till the car was on the ground, The out side tie rod end touched the in side edge (Beed) of the rim just enough to keep the wheel from turning.Looking at the picture your car looks lowered,Is it stock suspension? Also if this is the rear,Is it hitting the rear leafs when its on the ground?

 

Tie rod would be my guess as well, the new outer hoops are too wide and now they're bumping up against the tie rod. Without pics from the inside, that's my best guess.

 

The safety outers 15’s today are different than the originals. I had the same problem going to 6” wide on my 56 Ford wheels. You can get 1/4” really nice spacers (black anodized) that fit the hub and studs. They are not sloppy.

 

Do you want to try a different set of stock 51 wheels? I can't be that far away and I don't plan to use them once the car is complete. I can move the tires over to the slots now if the wheels work for you.

 

I know that Chevrolet went with a completely different brake system in '51; maybe the '50 setup had a different offset?

 

I appreciate the offer. I may hit you up down the road but for now I'm going to keep monkeying with what I've got.