So it's been 3 months, but thought I would follow-up...
I ordered a set of Pirelli MT66 tires back in Feb. They came with Jan 2018 date codes, and all scuffed up, so I returned them. Waited a month or so to reorder. Paid $180 for the pair shipped from Revzilla; best price I could find. The second set had late 2018 date codes.
Then being my usual self; making a simple job much harder, I combined installing the front tire with cleaning the front forks with new oil. BTW, the 6 lb. front fork air pressure is highly recommended on Progressive springs too, IMHO. Too much dive without it. So the front took me a week.
Then it was time for the rear tire and noticed the maintenance schedule for the drive shaft splines, so why not do that too? When I removed the shaft, I found what the Service Manual calls the "damper spring" to be missing. Fortunately, there was no damage to the spline ends. BTW, instead of Honda Moly 45 or 77 or whatever they call it today, I ended up using a Yamaha part instead (pic). You can get this LARGE tube for the price of 2.5 OZ Honda lube.
Just had to wait another week for a Western Honda order. When I had the propeller shaft out, then I noted where a squeak was coming from, that I had heard for awhile. The swing-arm bushings were dry. So now, I had to pull the exhaust system, then the swing-arm. That lock (castle) nut caused me to make a tool. BTW, a socket tool is enough (pic). I went and bought a made-in-china socket, instead of wrecking one of my made in the USA tools. Also, the china-crap steel cuts easier! The 1 3/16" socket OD is just under 40mm for a perfect fit.
I torqued the pivot-bolt to 14 lbs as per the manual, and marked position with a Sharpie. Then I was able to torque the lock nut to 72 lb+ and the pivot bolt stayed where it was, np.
Anyway, a simple tire change created complete service for both front and rear suspension and I'm finally on the road again. I've only had time to ride about 100 miles so far, but I will tell you that Dennis' suggestion for this brand of tires is right-on!
The balance and traction is far better than other GL1200 tires I have tried; both Metzeler ME 880 and Dunlop Elite 3 tires. Very smooth on the highway and I can lean much better on the great profile of these tires. Mileage is not important to me, so I'm sold already and for only $180 a set!!! Thanks again, Dennis