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Thread: dollar/mileage question??

  1. #1
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    dollar/mileage question??

    here is the question. Im buying two tires for the front axle on my truck (2wd). Im going from tires that weight 22.5 pounds each to tires that weight 17 pounds each for a grand total of 11 pounds reduction in rotating mass. How many more mpgs do you guess that will net me? thanks


    Last edited by kalifornia; 08-23-2013 at 04:50 PM.

  2. #2
    It's impossible to say for sure, because there are other issues in changing tires that affect fuel economy as well.

    EG: rolling resistance is a big one, and it's unlikely the tires have the same resistance. Could be better, could be worse.

    Also, it sounds like you may have changed size/width. And if you alter the vehicle's stance, you also affect its aerodynamic drag. Could be better, could be worse.

    But if you want a rough calculation and want to ignore the other issues just for the sake of running some numbers, the EPA says this about weight:

    An extra 100 pounds in your vehicle could reduce your MPG by up to 2 percent. The reduction is based on the percentage of extra weight relative to the vehicle's weight and affects smaller vehicles more than larger ones.
    Removing 22 lbs of static weight could mean "up to" a 0.44% boost in MPG.

    But it's often said that removing rotating mass has a greater impact than taking off static mass. The question is by what factor... let's say it has twice the impact. So then you're looking at the equivalent of dropping 44 lbs, or "up to" a 0.88% boost in MPG.

    Assuming all other variables remain the same (rolling resistance/vehicle stance). Which they don't.


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