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Old 08-21-2014, 12:59 PM   #1
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New f350 & f450 rpm question?

Anyone running the new 2011-14 F450 with 4:30 gears what rpm are you turning at 70MPH?
Or does anyone have the same year F350 that is running 4:10 gears. What's your rpm at 70MPH?

Hayden & Gigi
2008 GS Endura Max Toy Hauler
2014 F350 4x4 Lariat
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Old 08-21-2014, 02:11 PM   #2
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Other variables to consider are tire diameter and differential ratio, unless that's what your 4:30 number refers to. Also, 70 mph will really eat into MPG with the wind resistance of the trailer. It goes up exponentially over 60 mph.


Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI
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Old 08-21-2014, 02:27 PM   #3
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Go hereEngine RPM / Engine Speed Calculatorenter in your tire dia and gear data. It will tell you your rpms.

With stock 245/75/17 tires and 4.10 @70=2084 F350
F450 with 4.30=2186. Assuming it has the same 6th gear of .67
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Old 08-22-2014, 05:47 AM   #4
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The engine RPM calculator helped thanks. I'm currently running 245/70 19.5 its a 33" tall tire. I was just enquiring in the possibility I have to change my gearing or maybe go to a 225/70 19.5. I'm hooked on the 245's, running them right now makes the truck seem sluggish and I'm curious to see how they tow but will be hard on the truck, pulling the hills when I decide to do a trip in the mountain region. My 5er loaded is about 17000 with a GW of 18000.
I will be doing a trip for labor day weekend so I will see how she pulls before making a decision.
Hayden & Gigi
2008 GS Endura Max Toy Hauler
2014 F350 4x4 Lariat
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