If Maxis tires are as good as everyone says they are, then put four new ones on the road and continue to use the Goodyear Marathon as a spare.
Four new Maxis tires on the road give you the best odds for a trouble free trip.
The spare has been out of the elements and never carried any load. It could be used as a spare for a really long period. My father never put the spare on the road in his Lincoln Town Car for the first 10 years he owned it. Then he put it on and drove it for four more years. No problem.
Years back I had a friend that worked for Firestone (way before they became Bridgestone). He was an engineer at one of their plants and he told me they had a temperature controlled (and maybe humidity as well) store room where they kept an assortment of brand new tires including tires for small planes and even tires for model-T Fords that had the words "non-skid" for a tread pattern. These atypical tires were stored off the ground in racks basically forever just in case a need arose.
