Tire Size and Fuel Mileage Or???

[Drover]

Originally Posted by kawgpz550

I appreciate everyone's input!

In your opinion, if the brakes were slightly hanging up, could this cause the 25% decrease in fuel mileage?

My guess is that if they were not hanging up enough to cause a notable difference in how well your car coasted when not on the throttle or brake, then probably not. But if your car loses momentum notably more quickly when coasting, then it might indeed be the brakes. I've got that problem on my car right now where a sticky caliper is causing the right rear brake to drag enough that the pad has worn down and the rotor is being scored but not enough that it notably impacts the car's coasting momentum, and it hasn't made any discernible impact on my mpg. My car has a computer that calculates mpg to the nearest tenth of a gallon, and there hasn't been any discernible difference in mpg beyond the normal fluctuations I saw from tank to tank before the problem started.

[kawgpz550]

Originally Posted by Drover

My guess is that if they were not hanging up enough to cause a notable difference in how well your car coasted when not on the throttle or brake, then probably not. But if your car loses momentum notably more quickly when coasting, then it might indeed be the brakes. I've got that problem on my car right now where a sticky caliper is causing the right rear brake to drag enough that the pad has worn down and the rotor is being scored but not enough that it notably impacts the car's coasting momentum, and it hasn't made any discernible impact on my mpg. My car has a computer that calculates mpg to the nearest tenth of a gallon, and there hasn't been any discernible difference in mpg beyond the normal fluctuations I saw from tank to tank before the problem started.

I haven't really noticed that much of a difference in the way the car is coasting, however, we just replaced the brakes less than 5,000 miles ago and just had to replace them again last week . However, right after changing the brakes, that tank of gas almost appeared normal, but now it's back to the same thing. I'm starting to think SOMETHING is up with the brake system. My husband replaced both calipers this time...last time he changed the rotors.
So, for some reason it seems I am going through brakes a lot faster than I should. The car only has 39,000 miles on it. There really shouldn't be ANY problems with it this early on, but......
We'll have to check out the brakes one more time (still not sure if that would account for an almost 25% decrease in mpg, though), if that doesn't do it, we'll put the old tires/wheels back on and see what happens.

Thanks again!