Closed shoulder, highway rib is highest mpg such as MICHELIN LTX A/S. However, they do not have a reputation for off pavement traction. In that event I'd go with BRIDGESTONE
Duravis r500 or m700. I have gone to the LTX M/S2 due to a great deal on them (my last MICHELINS failed, and these were almost given to me). They have an open shoulder and seem to have better traction, but I imagine I have lost a bit on FE. The BRIDGESTONE tires would be my choice starting from scratch.
Duravis R500 HD Heavy Duty Tire | Bridgestone Tires
Duravis M700 HD Tire | Bridgestone Tires
Best tires will last longest (7-10 years and well past 100k miles) so understand premium price brings long term benefits, not just tank-by-tank fuel economy.
Driving for economy means longest tire & brake life, not just FE. They go hand-in-hand with safe driving . . . it's a win all around.
The BRIDGESTONE r250 would also be the best trailer tires. LT type. Get rid of any ST tires if one wants reliability, long life and premium performance.
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