I have a 2002 accord 4cyl. About 4 mos ago I put new tires on P205 (one size bigger) my mpg's dropped and I discovered they only put 28psi in so I aired to 34 and my mpg went back to normal 27.5. Then the weather changed and all of a sudden my mpg has dropped to 23--yikes! I checked and changed my air filter, tire pressure at 34, recent tune-up and timing belt changed. Could the change in tire size and winter fuel mixtures make that kind of difference in mgp?