[Marz]

My wife (who drives the Hemi "D" more than me), has informed me that her mileage around town has been an abissmal "9 mpg" as of late! Before I installed the 20" wheels and tires, and a Cat back exhaust, she was getting 11 mpg around town. She has been using the electronic roof console display to calculate. Now I know that switching the wheels and tires from original, would probably show a 2-3 mph discrepancy on the odometer, but is it possible that the new wheels and tires and the exhaust are fooling the trucks fuel mileage computer???

 

[finucane]

Even at 11 MPG maybe ask her to get rid of the lead shoes!
I thing in past threads even with the 5.7 the average is 15+ MPG in city and 19+ on hwy (trip).......
My opinion is she driving a little hard!

 

[05RamtoughHEMI]

my sister and her husband had a 04' Durango with 4.7, and only got about 15 mpg, they just traded it in last month for a niiiice Altima that gets 26-27 mpg, and there alot more happy with it, my broinlaw said that D was a DOG.

 

[finucane]

my sister and her husband had a 04' Durango with 4.7, and only got about 15 mpg, they just traded it in last month for a niiiice Altima that gets 26-27 mpg, and there alot more happy with it, my broinlaw said that D was a DOG.

And your point?

 

[05RamtoughHEMI]

dont really have one, it states the mpg of a Durango with 4.7, and some people dont like it, and they got rid of it. thats all.

 

[Lew360]

Yes the new tires and wheels can effect the Mileage. Depending on the overall tire size it can be way off. The overhead comp. and odo. is calibrated to the stock size tires. You can find a wheel and tire calculator to find out how far you have really gone and then calculate MPG manually. The over head only works correctly with stock (overall size) tires and even then it isn't exact. Tire Calculator

 

[IndyHemi]

easiest way I know is to divide the number of miles driven since last fill up by the number of gallons put in to a fill up. That is more accurate than the trip computer.

 

[Lew360]

easiest way I know is to divide the number of miles driven since last fill up by the number of gallons put in to a fill up. That is more accurate than the trip computer.

Yes, but his mileage will be off because the overall tire height is different than stock.

 

[IndyHemi]

Usually the difference is nominal. a 20" rim can have the the same circumfrence around the outside of the rubber as a 17". I don't know his overall sizes that he has so it would only be a guess either way. You do make a good point, though.