Never stretch the knee wraps out to the MAX when wrapping, even on your single rep maximum effort. always leave some room for the wraps to stretch as you squat, this will allow them to recoil and help blast you up out of the whole.
Let's say this is 1ft of unstretched knee wrap
______ 12"
If i stretched it out to the max it would look like this
____________ 24"
I always wrap when i get to 585lbs
_______ 14"
675lbs would be tighter
__________ 20"
700lbs and up would be between this
__________20-22"
The heavier the weight, the tighter the wrap, but never a full max'd out stretch on the knee wraps. They act like a rubber band to help pop you up, if their stretched to the max they will not recoil, they will only cut into you and hurt like hell with no real benefit.
just my .02, it works for me.
Also, in my humble opion, knee wraps should only be used when doing HEAVY triples or less.