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tire size? gear ratio?

Discussion in 'Ask An Owner Operator' started by ramsey, May 13, 2011.

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  1. May 13, 2011 #1
    ramsey

    ramsey Bobtail Member

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    hello guys im looking into becoming an o/operator im looking to buy a pete 379exd for otr but i would like to know about gear ratio does bigger number mean more gears or smaller number more gears, also what is a good gear ratio for good mpg, and does smaller or bigger tires get better mpg i was thinking bigger tires this example is for a car but think it was for a truck
    Think of this. Say you have a smaller 15 inch diameter tire.

    3.14 X 15 inches = 47.1 inch circumference.

    Now say you get a bigger tire. 17 inches.

    3.14 X 17 = 53.38 inches

    53.38 - 47.1 = an extra 6.28 inches of circumference

    That is a 13.3% more of a tire circumference over your old smaller tires.

    If the axle rotates the same number of times. You would end up 13% further with the bigger tires. In mind, this means that it should give you 13% more MPGs than having a smaller tire!!! Does this make sense?
    so my 2 questions are
    what tire size is good for good mpg 22.5 or 24.5?
    and what gear ratio do i need for good mpg but i also need some good torque i was thinking 355
     
    ramsey, May 13, 2011
    ramsey, May 13, 2011
    #1
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  3. May 13, 2011 #2
    SHC

    SHC Spoiled Rotten Brat O/O

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    Westville, IN
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    22.5 has less rolling resistance than a 24.5

    But, when I had 3.90 rear gears (22.5) I switched to 24.5 tires and dropped my RPM's by 150, but it did not gain me any MPG as I was now losing the gain of the lower rpm's due to the heavier tires. I mainly did it because I preffered to drive at 1350rpm than at 1500rpm.

    I currently have 3.55's in my WS with 22.5LP tires. I run 1,300rpm at 60mph and it pulls just fine. MPG isn't good but that is due to the engine and type of work I am doing (flat-top truck pulling a box van) and the big shinny bumper I put on the front doesn't help much either. Stainless is HEAVY!!!
     
    SHC, May 13, 2011
    SHC, May 13, 2011
    #2
  4. May 13, 2011 #3
    Krooser

    Krooser Road Train Member

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    Wisconsin
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    The proper gear depends on the engine to a certain extent.

    The CAT's with ACCERT will have been properly spec'd with a 3.25 or 3.36 rears (Eaton) or a similar gear of the truck has Meritor rears. Most PACCAR products use Eatons...

    An ISX or Detroit will generally have 3.55's or higher (slower top speed) in OTR applications.

    Your right foot is the biggest factor in MPG's...
     
    Krooser, May 13, 2011
    Krooser, May 13, 2011
    #3
    SHC Thanks this.
  5. May 13, 2011 #4
    MedicineMan

    MedicineMan Road Train Member

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    low pro 24.5's. why, because 22's on a pete are gay....


    3.30's for a cat, 3.50's for a troit, couldn't give me a cummiins


    the biggest thing is DONT buy a ten speed trans. 13,15 or 18 only. keeps it in the sweet spot rather then revving it up and bogging it down with every shift


    personally I think the accert cat is a POS, stay away from an 04 or 05 with a single turbo cat because it's an MBN bridge motor. quite possibly the worst fuel mileage motor ever built. My preference would be an older electronic cat or an early 2000's with a detroit. they haven't used troits in petes since lie 04 or o5 if I remember right
     
    MedicineMan, May 13, 2011
    MedicineMan, May 13, 2011
    #4
    SHC Thanks this.
  7. May 13, 2011 #5
    ramsey

    ramsey Bobtail Member

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    Feb 14, 2011
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    im looking for a 500hp troit for better mpg but cat is ok & then i can add really nice vertical stacks, texas bumper with lots of lights and then harwood floors and a nice sound sistem im looking to buy like in the next month or so hopefully i can find a silver black or maroon with american class int
     
    ramsey, May 13, 2011
    ramsey, May 13, 2011
    #5
  8. May 13, 2011 #6
    Les2

    Les2 Road Train Member

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    Oh this is just priceless!

    Where you from? I just want to know so when the bank comes to repo it I can buy it for a quarter of what you got suckered into paying..!

    This is a joke?

    Isn't it?
     
    Les2, May 13, 2011
    Les2, May 13, 2011
    #6
  9. May 13, 2011 #7
    Pokey1

    Pokey1 Bobtail Member

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    I REALLY hope this is a joke. None of that has any relevance to making Money.
     
    Pokey1, May 13, 2011
    Pokey1, May 13, 2011
    #7
  10. May 13, 2011 #8
    MedicineMan

    MedicineMan Road Train Member

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    and that 120" ARI makes money how?

    there's more to life then just money
     
    MedicineMan, May 13, 2011
    MedicineMan, May 13, 2011
    #8
  11. May 13, 2011 #9
    Pokey1

    Pokey1 Bobtail Member

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    Mar 29, 2009
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    Suited for the right application makes perfect sense.
     
    Pokey1, May 13, 2011
    Pokey1, May 13, 2011
    #9
  12. May 13, 2011 #10
    MedicineMan

    MedicineMan Road Train Member

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    Woodville, TX
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    hater.............. lol








    oh btw, I didn't say makes sense I said makes money
     
    MedicineMan, May 13, 2011
    MedicineMan, May 13, 2011
    #10
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