Getting all new drives, need advice on lowering RPM

Discussion in 'Ask An Owner Operator' started by georemo, May 13, 2021.

  1. georemo

    georemo Bobtail Member

    34
    24
    Mar 28, 2020
    0
    I'm getting 8 new drive tires and was thinking about switching to tall rubber to lower the RPMs.
    Truck came originally with 295/75r22.5G BR tires
    3.36 rear ends
    13 speed RTLO-18913A
    Volvo VNL780 D13 455hp EcoTorque
    most loads are 40k or lower, rarely 42-44k.

    Terrain is mixed, I-81 NY-Carolinas I-80 across PA, Ohio turnpike, Indiana Tollway, I-70 Ohio-Indiana I-90 NY
    I cruise at 65-75 depending on where I am, 75mph at 1600 rpms is killing my MPG and for a terrain like Ohio turnpike it'd be ideal to cruise at say 1300 or 1400

    and last, would there be any height clearance issues with tall rubber pulling a 53ft box? I currently make it under a 13ft4 close to where I park but not sure how accurate that is sign is.
    Thanks a bunch
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. Bean Jr.

    Bean Jr. Road Train Member

    4,380
    6,839
    Mar 30, 2014
    0
    I believe the diameter difference is 2 inches, which would make it ride 1 inch higher
     
    baha and georemo Thank this.
  4. WHY NOT

    WHY NOT Light Load Member

    156
    117
    Oct 18, 2015
    0
    tall tires may help lower your rpm but at 75 you're still pushing a bunch of wind. The gain on MPG will probably be very little. The best way to help is to slow down, keep the engine in the right rpm range climbing hills don't bog it down etc. I went from 22 lows to 24 low's with my 3.25's and dropped about 100rpm's. (24 lows are the same height as 22 talls)
     
    Bean Jr., slow.rider and georemo Thank this.
  5. DUNE-T

    DUNE-T Road Train Member

    5,232
    10,722
    May 10, 2015
    Detroit, MI
    0
    I have done the same experiment, mpg got worse, because I constantly had to downshift, since engine was not operating at the proper rpm
     
    baha, Brettj3876 and georemo Thank this.
  6. Brettj3876

    Brettj3876 Road Train Member

    7,363
    29,226
    Nov 18, 2014
    Canceling cancel culture/CCC
    0
    Yep. My uncle tried tall 24.5 and next tire change went back to the Lo pros
     
    Swine hauler, baha and georemo Thank this.
  7. georemo

    georemo Bobtail Member

    34
    24
    Mar 28, 2020
    0
    Thanks for the helpful inputs, I may end up giving it a shot and cruise slower at 68 mph, 1 inch height increase would be a bit of an issue though, as well is having to downshift often, but not sure if that would be an issue with 3.36 rear ends and the 13 speed
     
  8. slow.rider

    slow.rider Road Train Member

    1,659
    3,789
    Apr 4, 2017
    NYC
    0
    Tires with low rolling resistance can help some. What make and model tires do you have? Also trailer skirts and fins do help if they're an option. Another tactic could be to use 4 drives and 4 trailer tires.
     
    Last edited: May 13, 2021
    Bean Jr., baha and Midwest Trucker Thank this.
  9. Rideandrepair

    Rideandrepair Road Train Member

    10,070
    25,659
    Aug 8, 2015
    0
    Aren’t Lo pro tires supposed to have less rolling resistance than tall tires?
     
  10. Crude Truckin'

    Crude Truckin' Alien Spacecraft

    1,438
    3,370
    Oct 22, 2016
    Zeta Reticuli
    0
    Supposed to.
     
    Brettj3876 Thanks this.
  11. Brettj3876

    Brettj3876 Road Train Member

    7,363
    29,226
    Nov 18, 2014
    Canceling cancel culture/CCC
    0
    Not sure but I would think so? Less flex and all
     
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  • Draft saved Draft deleted