The "Rio boats" as the Clyde rivermen called them, were about the largest ships to discharge at Glasgow's General Terminus coming in at about 30000dwt. They never brought full cargoes as far as I can remember, not through any constraints on the Clyde but at their loading port, Puerto Ordaz on the Orinoco.
They were all built in Germany, RIO CARONI being completed in 1957.
This was taken in 1975 as she passed Greenock outbound.