What's wrong with my mileage?

[DaytonCobra]

Ok here is my question...

I have a 98 4door Explorer that has the 4.0 OHV and the 5 speed auto trans, 3.73 gear. It originally came with 225/70/15 tires and I recently put on new 235/75/15 tires on it. How much difference in speedo error is there with these tires?

I filled up last night, it took 14.6 gallons. According to my odometer, I had gone 184 miles. That is a whopping 12.6 mpg. Now this is 100% city, stop & go driving, zero highway miles and our gas has been switched over to the winter formula which generally kills about 2 to 3 mpg.

My mpg seems a little low and I'm wondering if the speedo error is part of it???

I also have a check engine code that is the left front o2 sensor...could this be part of the problem?

 

[DaytonCobra]

Also, the vehicle has recently had new plugs, wires, air & fuel filters, all fluids changed, etc.

It's ONLY got 260,000 miles on it, I'm sure that has nothing to do with it! Seriously, it burn ZERO oil and really runs great.

 

[00XLS]

With that mileage and city driving it sounds about dead on to me.

 

[aldive]

Faulty O2 sensors can indeed cause a drop in gas mileage.

Good luck .....

 

[00XLS]

Faulty O2 sensors can indeed cause a drop in gas mileage.

Good luck .....

I agree

 

[xiscarykidsix]

i wish i was getting that, im currently getting 8 mpg city and i just got one new o2 sensor, it flickered the check engine light, oil change, new tires, and spark plugs. what else could be the problem?

 

[stng_96]

I agree with above, if that is only city driving, then it seems just about right considering the other info you posted. I dont think those tires are a drastic enough change to affect it to much either

 

[Glen4X4]

I wanted to add, that explorers that came with 15inch rims came with 235's stock. I would definitely change the O2 sensors they're probably due with that many miles, check your air filter out.

 

[5.0B2]

the new tires are not much change from what you had - about 2 1/2 mph @ 30 and about 3 1/4 mph @ 60. about 3/4 of an inch more ground clearance. Not enough to cause a measurable change in mileage.