Or how did that work, period? I was thinking of a diorama with a King Tiger and a Steyr RSO, with a guy passing main gun rounds up. Would that be accurate?

Anything on wheels and an engine! Kubelwagens and even motorcyle/sidecar combo's were pressed into service to deliver ammo. More usually trucks or Maultiers. Ammo could even be shared from another tank of the same unit.

I kinda suspected that. I'm sure things were chaotic towards the end of the war.

Thanks

Don't forget all the munition schleppers - purpose built sdkfz 250s, panzer III/IV but also 38t, 35t, Renault tractors, at least one Nashorn that we know of, many captured tanks like T60S , T26, etc.

From what I have seen in photos it is generally a truck that hauled the ammo, placing it into a secure area the tanks would come back to for fuel and resupply.

Be careful of the munitions carriers. the new one, sd.kfz 252, was only, from what I read, used by the Stug groups as it was designed for the 75.

For Tigers it appears to be trucks mostly with the odd retro-fitted Pz-III's. That may be because of the size of the shells.

I would go with the most probable vehicles. Those would be trucks or Maultiers. By the time in the war that the Kings came along,the Germans almost never had the luxury of purpose built ammo vehicles.
J