Decrease in MPG by 1 point... Tires to blame?

Discussion in 'Ask An Owner Operator' started by Rubys0h0, Oct 15, 2021.

  1. Rubys0h0

    Rubys0h0 Bobtail Member

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    I used the Michelin rolling resistance comparison tool and it says there's only a 6-point difference between my old drive tires (Michelin XDN2 275/80 R22.5) and my brand new ones (Kelly KDA 295/75 R22.5)

    So then why did my MPG average decrease from 8 to 7?

    Is that even possible, or could it be a different problem?
     
    77fib77 Thanks this.
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  3. Long FLD

    Long FLD Road Train Member

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    How long is the 1 mpg drop average for? Also keep in mind you’re going from a relatively worn down tire to one with nearly an inch of tread on it too.
     
    Rideandrepair and beastr123 Thank this.
  4. Rubys0h0

    Rubys0h0 Bobtail Member

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    Nearly a full inch. These KDAs are thick as hell, super deep grooves.

    I've tracked the average for 8 full weeks at around 3000 miles a week.
     
    Rideandrepair Thanks this.
  5. Goodysnap

    Goodysnap Road Train Member

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    New tires can decrease mileage slightly. Deeper tread=more resistance. As they wear smooth with less tread flex and the lower the depth is when you can get your best milleage. Keep them air as hard as you can.
     
  6. jamespmack

    jamespmack Road Train Member

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    Compair revolutions per mile and adjust ecm to new tires.
     
  7. ProfessionalNoticer

    ProfessionalNoticer Road Train Member

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    Don't forget to rotate them every 20k to keep the feathering at bay while you deal with the new tire "squish". Aren't new tires great?!
     
  8. Midwest Trucker

    Midwest Trucker Road Train Member

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    Kellys are more of a farm tire IMO. Like if your hauling grain, running gravel roads, etc. So, you went from one of the best tires in the business to a mid range non OTR tire.
     
  9. lester

    lester Midwest's #1 Feed Hauler

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    You went from a high end tire to a middle of the road high traction tire
     
  10. Big Road Skateboard

    Big Road Skateboard Road Train Member

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    Exactly. You went from a premium to a mid grade tire. Fuel economy will suffer.

     
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  11. jamespmack

    jamespmack Road Train Member

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    I like and respect your content and knowledge. Higher psi is better for mpg, but decreases ride quality and wear. It is a mega fleet way of thinking. Need to really find balance that works for each individual operation. Every tire has a operation range.

    I run 95 in steers, and 90 on trailes and drives. It works just fine for my operation.
     
  12. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    I’ve ran a set of Kelly (8) drive’s tall rubber (11.24.5) KDA. Back then I paid $325 each brand new. It was a deal I couldn’t pass up. Had very good luck with them, but like stated above, when they start feathering, it’s time to rotate.
     
    Rideandrepair, Dave_in_AZ and Rubys0h0 Thank this.
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