Just to put things in perspective Jim claimed 285 when he first burst on the scene with the bulkier type look and that was also when he was clearly at his biggest.
It's not inconceivable that Ultimate Warrior weighed 275 but at his prime ripped condition you really think he was that much heavier than a prime Arnold?
If Vince McMahon, notorious for over promoting size, sends you out there with a billed height of 6 foot 2 you damn sure aint 6'4 or 6'5.
Bodyweight can be a difficult thing to estimate by eye especially for bodybuilders. Most top bodybuilders are short - 5'9 or under. They also carry very low bodyfat levels on stage. Top bodybuilders very often have "slight" frames also - this may seem counterintuitive but they very often have a small skeletal structure, small joints, waists etc. Most bodybuilders started of as ectomorphic skinny kids, with naturally small frames. For example a guy like Flex Wheeler at his peak was only around 230 I believe, yet if somebody said he was 260 I would have no trouble believing them.
In contrast most pro-wrestlers are the complete opposite. They naturally have heavy frames, thick joints, wide shoulders, big hands, wrists etc. They are usually over 6'0 tall plus carry more bodyfat then a competitive bodybuilder, even a shredded guy like Warrior.
For example, this picture. Superstar Billy Graham was billed as 275 throughout his career. This was taken during the 70's when Arnold was at his largest. I'm an Arnold fan but he looks like a pissant next to Billy Graham here. Warrior was not quite as tall as Billy Graham but was of a similar size.