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
Getting all new drives, need advice on lowering RPM
Discussion in 'Ask An Owner Operator' started by georemo, May 13, 2021.
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I believe the diameter difference is 2 inches, which would make it ride 1 inch higher
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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. -
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. -
Swine hauler, baha and georemo Thank this.
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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
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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. -
Aren’t Lo pro tires supposed to have less rolling resistance than tall tires?
Bean Jr., Brettj3876 and Crude Truckin' Thank this. -
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