This wouldn't amount to much in your case but oversize tires will make it seem like you are getting less mileage than you are.

 

Oversized/undersized tires will not make MPGS appear to change. They will definatly change your MGP a fraction. But I guess your are reffering to the tire size odometer error induce by tire diameter. I''ll get theis backwards but, 1 mile on oem tires is a little shorter distance than 1 mile on bigger tires, the bigger the tire the more the difference.

 

Your 1 mile statement is wrong. 1mile=1mile .
Shorter tires travel a shorter distance per rotation than larger tires is right.

 

1 mile as read by the ODO meter, is what I meant.

 

Everything has pretty well be covered. One thing to think about, especially up in the north, is that we're still on winter blend fuel. We always get worse mileage in the winter because of this. One thing you can try is running non-ethanol gas. Here's a database of stations around the country that sell it. Now, it's not a complete list, I'm sure, but it is pretty good.

www.pure-gas.org