Many folks "forget" to pack their bearings and roll on old tires just fine. How? I have no idea.
On the other hand, We tow about 5000-6000 miles a year. Year one, had the bearings serviced/greased. Year two, packed. When they are packed, the brakes are inspected too. The difference in cost was about $150. I absolutely hate roadside breakdowns.
If tires have uneven wear, there may be a bigger problem than just the tires. Brakes, bearings, or axle issues to name a few.
It's the heat/cold cycles (and time) that kills tires. Tread depth is a false indicator of a good tire. Properly inflated and operated within their specific Load and Speed Ratings will get most tires to their 3rd year.
2016 Jayco 23RB
2006 Ford F-150 Supercrew 4x4 5.4