Highest bite force of a wolf?
The range from mean to maximum of wolve's bite force is huge.


Is it really? According to this Wikipedia page, (Scully, C. (2003). Oxford Handbook of Applied Dental Sciences. p. 151) claims that human masticatory forces range from 70 N to 700 N. Also, (Kim et al., 2018) claims that domestic dogs have a bite force of (147-3417) N, so I don't think it's too implausible for wolves to have the value of (774-2255) N of wolves that @Olga_Swider claims. We see also, on Table 4 on p. 550 of (Eng et al., 2013), the estimated maximum bite force (MBF) spread over the $M^2$ area of the jaw. Eng claims that Gorillas and Chimpanzees have MBFs of 3200 N and 1800 N respectively. I think there's quite a large degree of control of masticatory muscles, which wouldn't make it too surprising that you can have a large range of forces.


  This range of wolves' bite forces could put them on par with big cats.


According to p. 621 of (Wroe et al., 2005), lions have a bite force of around 1768 N, while tigers have a bite force of 1525 N. So, it seems that wolves have a significantly smaller mean bite force than big cats. But bear in mind that while dogs and wolves might have a fairly similar jaw size, lions jaws are much larger so their bite force is spread over a much greater area. So exercise caution when comparing them. Similarly, note that PSI is a unit of pressure (force over area), while newtons are a unit of force.


  Why isn't there a maximum bite force for wolves?


Says who? Of course there's a maximum. Wolves can't make arbitrarily large forces with their mouths, that's physically impossible.