That's what I'm thinking. A 21mm is too small, but a 22mm is too big. BTW, Costco used a 22mm to change my tire, probably Discount did the same. A 7/8" is 22.2mm, so is also too big. I found a "flip socket", which is 21mm/21.5mm, which may do the trick.
Also, I have my oil changes done at...