Quote:
Originally Posted by basslover911
Since I am on the subject...
Anyone changed to a tire 10mm or more narrower and have mpg data?
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The problem here is "everything else the same!". Everything else is usually not the same.
Even if you keep the tire brand and tire line, the rim diameter, and the aspect ratio the same, the load carrying capacity also changes. Since load carrying capacity seems to be a major factor in rolling resistance, only the width change should result in a slight increase in RR - worse mpg! But this change is so small that it is doubtful you can actually detect the difference in a vehicle.
In your case, it looks like you have only kept the rim diameter and the aspect ratio the same. In other words, you've also changed tires as well as used a narrower width - and this complicates the issue too much to make a prediction.
But you should be aware that - everything else being equal - new tires are always going to hurt FE compared to worn out tires.