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Old 01-07-2019, 07:23 PM   #1
elprofesor86
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F250 tow vehicle

I just purchased a 3730FL with a weight of 13328 and GVWR of 16670. I tow with a 2017 F250 diesel and a gear ratio of 3.31 which is rated at 14,700 lbs. I can re-ratio my axle to 3.73 and I'm curious to know if anyone has done this? Any advice will be greatly appreciated.
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Old 01-07-2019, 07:35 PM   #2
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If you have a 4X4 you must regear both the front and back. That will not increase your tow manufacturers capacity it will increase the weight the truck reasonably can pull.
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Old 01-07-2019, 07:53 PM   #3
elprofesor86
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Thank you!

I understand and I'm ok with not meeting manufacturer's capacity. It is a 4x4 and I have a transmission shop that will do the work on both axles. I really would like to know if anyone has converted from 3.31 to 3.73 and if they noticed a difference.
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Old 01-07-2019, 08:00 PM   #4
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If you feel safe fine. I would. I’m sure you would notice a difference but you probably have plenty of power to pull your camper. I remember when these trucks had 400 pound feet of torque and pulled 12000 pound campers you have over 900 pound feet and a 6 speed transmission to go with it.
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Old 01-07-2019, 08:19 PM   #5
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Thank you!
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Old 01-07-2019, 09:53 PM   #6
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Those aren't the only figures to watch. You're tongue weight may be more than the tires on a SRW are rated to carry.
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Old 01-07-2019, 10:25 PM   #7
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I had a 1993 cummins diesel with 400 pounds of torque and it towed my 29' 5th wheel very good but these newer 5th wheels are much longer and heavier but I think the 'Big Three' have more than kept up with the extra weight by more than doubling the horsepower and torque. I agree with DQ in that the tires and wheels are probably not adequate for the weight on the rear. I would get some tires and wheels with the same capacity as an 1 ton SRW truck.
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Old 01-08-2019, 12:51 AM   #8
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Quote:
Originally Posted by elprofesor86 View Post
I just purchased a 3730FL with a weight of 13328 and GVWR of 16670. I tow with a 2017 F250 diesel and a gear ratio of 3.31 which is rated at 14,700 lbs. I can re-ratio my axle to 3.73 and I'm curious to know if anyone has done this? Any advice will be greatly appreciated.
I think you'll benefit from 3.31 to 3.73s. If you were at 3.55 I'd say no. I have the 3.55 and it pulls great. I live east of Tahoe and south of Carson and there are 6-9% grades all around. My old trailer (14k) I could pull grades at 65mph easily. With this trailer at 17k, it slows to 55mph near the top of those grades.

On the wheel/tires, they are likely the same as the F350 variants (same part numbers). Probably 3500 or 3640# per wheel rated. I haven't seen aftermarket wheels rated higher nor have I come across published data for the factory wheels. That's likely the lower limit on how they arrive at the 7000 or 7280 RAWR on the door stickers. My 285/65r20s Nittos are 3860# per tire @ 80psi. Stock 275s are around 3750 @ 80
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Old 01-08-2019, 06:52 AM   #9
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My 2012 F350 with 3.31s handles our 3791RD just fine and we CAT scaled at 16.8k.
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Old 01-08-2019, 07:57 AM   #10
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With a 2017 you are at 440Hp and 925 lb ft torque which well exceeds my 2011 *400/800). That 2011l, with 3.55 gears, pulled our 12K High Country up any mountain we wanted coast to coast - and most were not interstates.



You already are aware that you exceed the 'B' pillar sticker so I wont go all weight police, especially since I exceed it as well


If the '17 has an optional and heavier capacity tire as the '11 has, that would be on my upgrade list. If you truck does not have an OEM rear sway bar and only the OEM wimp on the front, I suggest you look at the Helwig heavier versions, Then air bags also help things too with Firestone and Air lift being the two niggies. Other then that, your truck really doesn't differ much from an F350 with the same power though another leaf in the springs and a 4" rear leveling block vs a 2" ( and that too depends on the truck as manufactured )


With that said, I would give the truck as it sits a length trip pull trial before spending 2-3 thousand dollars on new gearset. I suspect that you will be surprised how well it tows your 5er.
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Old 01-08-2019, 08:31 AM   #11
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I have 3.31's in my 15 F250 and I have no problem pulling my 13,000# Montana 03 3280 RL. I have been coast to coast and the truck pulls just fine. I was concerned about the gearing also but towing 30,000 miles so far without issue. I would leave it alone save your money. Buy the wife something nice. Maybe she will give you something nice in return. LOL
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Old 01-08-2019, 02:40 PM   #12
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just try what you have. if anything, up your tires to the next larger tire size.
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Old 01-08-2019, 10:02 PM   #13
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Thank you and more importantly, my wife thanks you!!
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Old 01-08-2019, 10:53 PM   #14
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I have LT275/65R18E tires on my truck rated at 3415#. I think I will upgrade my tires. Any suggestions?
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Old 01-09-2019, 05:04 AM   #15
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These things have been tested all over the this continent and others, and the engineers found these to be the best ratios to offer, so my advice is to take off and drive it the way it is. These trucks will do amazing things the way they are. I'll bet you will be just fine anywhere you go with that weight. (Not the weight police, but you understand the 250s limitations on paper-err-door sticker)
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Old 01-09-2019, 07:56 AM   #16
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Originally Posted by elprofesor86 View Post
I have LT275/65R18E tires on my truck rated at 3415#. I think I will upgrade my tires. Any suggestions?
When I got my new set of tires the weight was a factor for me. 3415# was the heaviest tire I could get in the size for my truck which is 18 " wheel.

So with 2 tires with that weight capacity you can carry a load of 6830#. When I went to the scale I was around 5500#
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Old 01-09-2019, 08:06 AM   #17
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Originally Posted by elprofesor86 View Post
I have LT275/65R18E tires on my truck rated at 3415#. I think I will upgrade my tires. Any suggestions?
Yes. Go on line and find a set of used 20 inch wheels. Kids are always “up grading” their wheels. You can buy a set for a fraction of what new wheels cost. They will usually be off of an almost new truck. The 18 and 20 inch tires are within 3/8 of an inch in diameter so the side wall is an inch less giving you better stability. The 20 inch tires are more expensive, that is the down side. The tires are rated for 3750 pounds each.
I just bought a set for $1000 to get the Michelin tires. I sold the wheels for $300. So I have $700 in a new set of Michelin tires.
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Old 01-09-2019, 08:24 AM   #18
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I have LT275/65R18E tires on my truck rated at 3415#. I think I will upgrade my tires. Any suggestions?

Move up to LT275/70R18 and you will move the rated capacity to 3640 pounds/tire. Stick with a brand you are comfortable with. The OEMs on my past two trucks were Continental which wore like iron but like the past Goodyears on earlier trucks got squirrelly on wet roads. I tried Firestones but they wore very quickly (~30K) but held up otherwise. The current are Michelin Defenders and at 35K miles are so far the best for my needs - others will, of course, differ
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Old 01-09-2019, 12:23 PM   #19
elprofesor86
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tires

Thank you all for your recommendations on tires. I've noticed that the total weight capacity of all those recommendations is about 14,500 - 15,000 lbs. Is that enough for a trailer that is rated at 16,500 fully loaded? I doubt I'll ever be fully loaded but want to be safe.
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Old 01-09-2019, 12:33 PM   #20
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I'd say yes. The first time I rolled on the CAT scale a week after I took delivery of my 3790RD, it showed 13.5k on the axles and an approximate pin weight around 3.5k on my 3790. I do have a 5500W Onan and four GC batteries up front that adds 500-600# to the front of the trailer and I have a 30gal Transfer Flow tank/toolbox in the bed of the truck. The rear axle on my F350 weighed in at 7440#. It's a little over the sticker rating, but I replaced the stock tires with LT285/65r20 Nitto Terra Grappler G2 tires are rated at 3860# per tire. I haven't got more than 32k on a set, but they have a 50k mileage warranty.
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