gear ratio.

I just bought a Ram 2500 Hemi with the 3.73. It has good power. Most diesels have a 3.43 in them I think.

My 05 has 4:10 gears which I feel is overkill in most cases when pulling about 10k. I will say on a 9 or 10 percent grade its handy but I don't often see that. Also as I understand the newer trucks have more speeds in the transmission which can change what is needed in the rearend. I feel a 3:73 is a good match.

If you do go diesel, gear ratio is less of an issue; yes, a numerically higher ratio provides more wheel torque, but the primary reason folks love to tow with diesels is they produce their torque at much lower RPM than gasoline engines...so, a diesel doesn't "need" low gears to get into the optimal powerband as a gas motor may.

Also, as powderman said, newer 5-and-6 speed automatics make rear end gearing less of a factor than with the older 4-speeds. Likewise the crazy amount of power these engines produce; with 800+ ft/lb of torque, lower gears just simply aren't as necessary as before.

3.55 or even 3.31 would be fine. If you ever think you are going to tow real heavy then I would get 3.73. You will save some fuel with the 3.55/3.31

With 800-ish lb-ft of engine torque, you likely won't notice any difference between 3.31. and 3.55, or 3.73. You will probably be stuck with whatever it has based on tire/wheel size for 2011+ Fords. No one has complained about the power of any 2011+ diesel regardless of axle ratio offered. Pick the trim/options/wheels you like and tow happy.

You don't have much choice with Ford and no choice with GM diesels. So with Ford if you are wanting to size your truck for a large, over 16000 lb, rv get an F350 dually and it will have 3.73 gears. All Duramax pickups have 3.73 gears. If you want a Ford SRW your choice is 3.31 or 3.55. Often the 3.55 equipped truck will have the 20" tires which are not available on the 3.31 equipped trucks. With the larger tires and lower speed ratio the end result is that your engine rpm is fairly close one to other anyway. Even so the 3.31 gears on the Ford provide a little better mpg than what you will get with 3.55 gears. Not pertaining specifically to your question but if you are buying a Ford srw diesel to tow a fiver avoid the f250, it has very little payload.

If you're getting a new Ford with the 6.7L, I don't think it would matter. The new 6-speed and the ridiculous amount of power compensates for any gear ratio out there. 9,000 lbs. is nothing to worry about.

My toy hauler weighs over 18,000 lbs. loaded and I have a 4.30. Biggest waste of gear ratio out there for this truck. I wish I had the 3.73 even with that big of a load.

muddyriver wrote:
hey all, I'm looking at purchasing a new tow vechicle. I believe I'm going diesel, but wondering what people think a good gear ratio would be for towing 9,000lbs. I see most 3/4 ford have 3:55. I was thinking at least 3:73. what are the thoughts?

You need to know more than just the gear ratio. You need the transmission ratios and so forth in order to understand the final drive ratio. It isn't as simple as just knowing the gear ratio anymore.

For example, my 3.42 (6 spd) 2010 Suburban pulls better than my 4.10 (4 spd) '05 Suburban did. It is because the ratios in the 6 spd tranny produce final drive ratio that are more useful for towing.

CTD and don't look back.

#40Fan wrote:
CTD and don't look back.

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