Staggered wheels mpg drop??

I have a 2016 Ecoboost and just bought a set of 2017 GT premium staggered wheel set. The look is fantastic! The ride is a little firmer which is fine but my mpg dropped from 29 to 24. I was surprised to say the least. The sizes are the correct size. I swapped the tires back and its right back where it was. Anyone else have that issue? I was going to put Brembo brakes package as well but now Im having doubts.

Bottom line The car rides and handles better and gets better mpg on the stock premium wheels. What am I missing?

DW

How long did you drive on them to get an mpg basis? There should be very little to no change in mpg.

Drove it for a week. 2 tanks of fuel. When I switched the tires back it went right back to where it was.

firedaniel said:

Drove it for a week. 2 tanks of fuel. When I switched the tires back it went right back to where it was.

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Yup same problem for me I was averaging 38 mpg on the highway with the stock 18's when I switched to the performance pack wheels the best I can get is 34 mpg. But for me the looks are worth it lol

38? what ya got?

firedaniel said:

38? what ya got?

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Base ecoboost

Physics 101: wider tires=larger contact patch=more friction with the road...

Also, is the overall wheel diameter comparable to the stock tire size? If not, you're probably getting inaccurate info from the PCM and the trip computer...the PCM can be re-flashed with the appropriate tire diameter ;)

Not only a larger contact patch but also a good deal more rotating weight.

Yeah the weight increase was definitely felt! The speedometer is now off 1.5 mph not a really big deal I think.

The diameter of the tire is less than the stock?

slink914 said:

The diameter of the tire is less than the stock?

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Bigger so now if my speedo say 75 it's actually going faster

if your speedo is off by 1.5mph, this will have an effect on the calculated mpg's. If you get the speedo error corrected, you will then have a more accurate mpg calculation.

Like said above, a wider tire equates to worse gas mileage. A taller tire should have little to no effect on gas mileage.

Also, if your tires stick out past the fender, wind resistance.

Taller tire has a lot to do with MPGs, especially what's calculated by the computer.

I don't know how the PCM calculate distance traveled. If it is by rotation, then wheels with larger diameter will make the PCM under-calculate the distance, if parameters for the original/smaller wheels are used. This will result in less mpg. Just my speculation.