My 2014 corolla just turned over 60K miles and I had the tranny fluid changed at my dealer for a total of $220 . Just wonder on the 2014 and newer how much were you charged for a tranny fluid change ?
To answer your question though winter blend does not get as good gas mileage as a summer blend gas. And also in cold weather because your car takes longer to warm up than in winter it accounts for more gas use.
About 10k back I had Kumho t11 tires installed at Discount Tire . Very good tire and you save a good deal of money over some others. They are well liked in "Consumer Reports".