John,
I have to admit, looked at those tires. Look well designed and built for what they are. BIG issue I had with these, Sumotumo/Mazam tire is the actual wieght. TW's were 75 lbs, S/M came in around 65 lbs. Majority of other brands in the 52-56 lb range. Stock 265-65-18 P/XL load range sizes were in the mid 40 lb range. Being as this is for a GM 1500 with a V6, wieght and inch bigger diam would kill power gearing etc. Those two tires brands got thrown out. IF they were going on a 25/35+ series higher powered truck. Where the wieght is not as big of a factor, I would consider both of these tires. I have used recycled/treaded tires like TW in the past.
As noted, Sumotumo builds the Mazama brand tires for Les Schwab, which their are probably none in New England area where you are. Mostly here on West Coast US.
Marty