Mike was also fit year round, so I don't think his weight fluctuated a whole lot. That being said, I would guess 215-225
I think asking what his "walking around weight" was and what his "prime weight without cutting" was, are 2 x different questions. I doubt he cut weight to make the weigh in, because he had no reason to. Rather, I suspect he just trained & ate (during his prime) in the way his team believed was most conducive to being in optimum shape on fight night, and weighed what he weighed come the weigh in. Granted, that training & diet may have resulted in him losing weight, but that's different to my understanding of the term "cutting" weight (apologies for being such a pedant!). Therefore, I believe the answer to the question "what was his prime weight without cutting weight", is the same answer to the shorter question, "what his prime weight"? His prime weight was c.215-221lbs. I can't be as confident of his walking around weight. Atlas is on record as saying Tyson was 190lbs as a 12-year old (that's the same as me at 41 & I'm around an inch taller than Tyson, probably 2-3 inches taller than he was when he was 12) & no doubt he was naturally an extremely heavily built young man. However, my guess is that the extent to which his training, diet & supplement increased muscle mass (that's not just muscle size, but hardening muscle also makes is heavier), was roughly offset by the degree to which they reduced the weight of his body fat. Therefore, my guess is that during his prime years, Tyson's natural, out-of-training-camp, walking around weight would have also been around 220lbs. I'm not as confident in that guess as I am in the answer I gave in my previous paragraph, though.
Out of camp he would get as high as 230 or so and then train his way back down to his fighting weight 216-220.
He got chubby between fights even in his prime. You can see how puffy he got sometimes in some of his sparring footage. His best weight imo was 215-218. The lighter he was the quicker and more elusove he was. I actually thought he looked the best in the 3 fight stretch from biggs to tubbs when he was at his lightest.
There is no reason to cut weight as a heavyweight. He was at his best 220 or under but likely put on 10 to 20 lbs between fights.
Tyson got fat here and there. Especially towards the end. There is a story about him destroying and paying for all the mirrors in a gym because he didn’t want to look at how out of shape he got.
Mike wouldn’t have expressly trained his weight down but his weight would’ve come down as an obvious byproduct of training for a fight. It’s such a multi faceted question. Some fighters weights come right down via training for a fight and then they blow out between fights. No happy medium to latch on to. It’s depends on what you really want to know - for me, I’d like to know what Mikes walk around weight might’ve/could’ve been without training but also without carrying significant excess weight. Could Mike have walked around at say 230 lb without it looking necessarily untidy?
This is all up to your usual standard of excellent exhaustive detail! However despite reading much & lifting for decades, I have never heard about "hardening" muscles as a thing. Other than as a kid the crackpot idea that light/less dense softer weights give softer muscles than steel... Muscle weighs more/is more dense than fat. But exactly do you mean by hardening muscle? Besides drying out/losing water, what can that mean & how?
Making muscles denser would have been a better description than hardening. It's possible to increase muscle mass, without increasing size, by making those muscles more dense. Toning muscles is probably a more common phrase.