I recently noticed I have been burning a lot more fuel. I changed tire sizes a while back. I went from 275 70r17 to 265 70r17. The new tires are all terrain tires. Could that cost me nearly 2 miles per gallon?

 

Not if you went down in size it shouldn't.

 

Hmmm....anybody have any ideas?

 

did you do your calculations correct? have you been driving differently (ie testing the new tires out in mud, sand, etc)?

 

Double checked the math hoping I was wrong. I drive the same route to and from work every day and I haven't had it off the pavement yet.

 

This is just a fart in the wind but fuel leak anywhere? has it been driving smooth as usual?

 

I have not noticed any leaking fuel and it seems to be running pretty well. I don't think the plugs have ever been changed. Could that cause the mpg to drop if one of them was bad?

 

gas stations change to winter fuel blend?

 

I usually see a hit this time of year. Have you been starting your truck to warm up in the mornings? Have you been driving different? Using the heat while driving? There's a lot of little things that can make a difference. Having a more aggressive tread should drop your mpg a tiny bit but I doubt that much. Have you been trying your new tires out in the woods? That can hurt mileage too. When's the last time you changed the spark plugs or air filter? How much PSI is in your tires? I doubt it's a major problem, probably just some new habit from the time of the year, something minor or maybe even the type of gas you're using.

 

I live 20 minutes from the Gulf of Mexico. I don't know if they use winter blends around here. I do not know if the plugs have ever been changed. I will get them changed and see what happens. The tread is a lot more aggressive but the tire is narrower.