A couple years ago I had to replace the front tires on my '15 because the driver side Universal T driver was nearly worn through to the air. Ten years on that pair of tires, and around 5000 miles seemed pretty good.
I bought a pair of Firestone Non Skid 30 X 3 tires to replace the T Drivers. After about 1000 miles the driver side was wearing erratically, which I determined was caused by the wheel being out of round.
Now I owned one T Driver and one Non Skid with lots of remaining life. I decided to buy a T Driver for $160 instead of a Non Skid at $264.
Comparing my old tire to the new one I found a couple differences.
The clincher portion of the tire on the older one fills the rim completely. The new tire is about 1/2" less rubber on each side. The old one had to be notched to clear the valve stem in order to mount the tire to the rim. The new one easily clears the valve stem. By the way the tubes are at least 25 years old, they have worn out several sets of tires.
Looking at the tires they seem identical for the most part. Both are marked 30 X 3 "Oversize"
Both are marked "4 Ply"
Wait, here's a difference: