I never get noticeable shrinkage from a cold wash. At most they go back to pre stretch measurements then stretch back out with wear. I get pretty minimal shrinkage with hot washes. I just washed my new UHRs and they didn’t shrink much at all. If you’re looking for maximum shrinkage throw them in the dryer after a hot wash. I promise they won’t explode.
As a rule though I wear until smelly, wash cold inside out, air dry outside then turn outside in.
I’m thinking more the inseams. I don’t really want to lose more than an inch, but worrid I’ll get a lot more