My personal experience suggests that a dog's bite pressure is directly related to how much he is trying to hurt you. A dog that is stressed and "fighting for his life" bites hard, where a dog that is "playing" bites with just enough pressure to hang on, if that. The dogs that bite the hardest usually won't run 50 yards to bite you, but if you "attack" them, they put everything they have into the fight. Take a breed that is fairly consistent, say GSDs. There is still a ton of variation in the bite pressure based on mood in the dog. Way more than 5%. More like 200%. My female malinois often times flies off the sleeve through lack of pressure. My male is 1/3 larger but bites way harder, feels like 3-4 times harder. (I made the mistake of letting him bite her soft sleeve on me one time, so I learned the hard way just how hard he is biting. I really thought for a few seconds that he may have broken my skinny little arm) Personally the dogs I have seen with the hardest bite pressure were rotties, but they are also usually more defensive, less prey motivated dogs. If you can get a pit to bite a sleeve, it's usually out of prey, as most pits want nothing to do with biting a person. So pits don't bite as hard as rotties as a general rule. And of course, training can condition a dog to bite hard or even teach him that increasing the pressure allows him to win, making bite pressure at least partially learned and conditioned. In any case, I got a nice little "soft" bite from a Labrador one time and I can assure everyone that bite pressure isn't all that when you're not wearing protection. Maybe it was only 100psi, but those **** canines went through my wrist like butter and I got to spend $500 and an afternoon in urgent care cleaning that bite up. No fun.