I don't know how anybody gets that kind of mileage out of a motorcycle tire. I'm very envious. I've owned over 100 bikes, and tried many hundreds of different tires. Even when I've babied the daylights out of the bike to try to maximize mileage, I almost never get much more than 3,500 miles out of a rear tire, and 6,000 miles out of a front. Over decades of riding, that's become my routine. Mount up new tires, when the rear is worn out the front is about 1/2 way worn out, so I replace the rear only. Then another 3,000 miles or so, they both get replaced. I must be a very ham-fisted rider, but no matter the tire brand or type, that's as much mileage as I get out of a tire.
On my DR650 I found good performance and decent mileage with the TrailWing TW22 on the rear. About 3,500 miles, which was pretty good for me. After a couple of those I am now trying a Shinko 705 on the back. I've tried the Heidenau K60 Scout, and a Mitas, convinced that there was a connection between price and wear, but I have not found that to be the case. Same with road bikes, touring bikes, little backroad screamers. I can ride them as hard as I want, or baby the heck out of them, and they all wear out tires at around the 3,000 rear, 6,000 front rate. I can't figure it out. I thought it was speed; that riding 100+ mph was killing my tires (back on a SV1000s, or an F800ST), but they wore the same as my DR650 or DR350 that can't get close to those speeds. So if you have some secret to long tire wear, I'd sure appreciate you sharing it.
I don't know what the "secret" of long life for tires are either. But that being said, I have a log book to document EVERYTHING I do to my bikes. The log shows that I got the following mileage on my tires:
Bike: 2009 DL1000
PR3 front - 23,XXX miles
PR3 rear - 13,9XX miles
Current PR4's that are still on the bike:
PR4 front - 15,3XX miles
PR4 rear - 12,XXX miles
The current PR4's include 5K+ miles from Honduras to Florida in October-November 2018
2K+ mile 80/90 mph mad blast from Lakeland, Florida to Austin, Texas and return in 4 days to watch the COTA MotoGP race in April 2019. Tese two trips were fully loaded panniers, top case, tank bag and my 6'2" 212 lb ass.
The rest of the miles are daily run around and short trips around Florida.
Last I checked a few weeks ago, both tires still have 2mm or more to get down to the wear bars, maybe a little more.
The only care I give to the tires is keeping the pressure at 36 front and 41 rear (+/-) all the time regardless of load, checking it every couple of weeks.
PR5's will go on when these 4's wear out.
Go figure, maybe it's magic?