Lug nuts

So today I decided to rotate my new tires after 5000 miles. 2013 pre runner 6 lug.
I had a 21mm deep socket from AutoZone I used before but this time it didn't seem to fit correctly. I finally used a 7/8" deep to finish. Used my new Milwaukee impact.

are they 21mm and does a certain socket for better?

 

They are 21mm. Maybe the chrome is starting to swell from rust on some of the nuts causing the size discrepancy.
I've seen this way too much when I worked at Jeep.

 

Rust and wear, especially from impacts, can change the dynamic.

 

I need to replace a couple; can I pick up some at an Autozone?

 

I bought some at Autozone last summer when I did my front wheel bearings. They are rusted already, and they seem to have a soft decorative shell on them. I'm looking to replace them, FWIW.