I also purchassed a set of those rims from another member......they are round though.
Anyways, even though you have a smiled rim the tire is likely running true.
Usually, only the bead area gets deformed and it doesn't carry out across the entire rim.
All that aside, my younger son owns a speed/accessory shop and he does all my various wheel/tire mounting balancing for me.......except for balancing these type.
He tried, I'll give him credit, he used every variation of adaptor he owns (he mounts up a fair number of those gigantic 24 and larger things....good equipment) but he could not come up with a combination that would center the rim adequetly.
So, I took the mounted assemblies over to a local Discount Tire as they are the one operation that always has the adaptors for balancing this rim.
I've been told that some Goodyear operations have them now as well but it seems dependent on the franchise operator.....my nearby Goodyear place looked at me as though I had three eyes when asked about the adaptors.
So, anyways, I would say you'll have success if you can find a Discount Tire nearby.
Judging by the amount of weight I see on your rim in the photo you can rest assured they are incorrectly balanced.....especially if there is a corresponding amount on the inside.
Discount used small tape weights on the outer edge towards the backside of the spokes and hammer on rim weights on the inner lip to prevent weight damage to the chrome.
Looks good, no weights visable.