@tiger862 - get a
Jaco Tread Depth gauge and a nice digital gauge. This
Etenwolf tested well on Project Farm and I can say matches my Jaco Elite Digital.
I use the depth gauge across tire monthly. If center is wearing more, I need to reduce 1-2 psi. If edges wearing more than I need to usually bump up by 1-2psi. The depth gauge is nice as it has the tick marks between each 1/32". They make digital versions but that also gets crazy. I used one of the
stick version depth gauges forever but the Jaco makes it easier to tell between the 32's. It may help you see if you need to rotate more frequently also.
Consider Costco in future for choices as you can have them rotate, document and may be more helpful for issues. They include 5 year road hazard and have free mounting as well as repairs. Sam's in NY no longer offers road hazard but other states do. Discount Tire you have to pay for road hazard but they also do free repairs, not sure on rotations.
If I didn't get the great deal from Mavis, definitely not my place to go just like Firestone for car care.