D60 3.55s stock size tires or 4.10s 33 and up tires

[JAKRANCH]

Hi all. I'm hopefully getting some free 33in tires and I'm hoping to swap to a d60 in front. Currently running 3.55s and have a nice balance of power and fuel mileage. How bad will the bigger tires kill my towing capacity without switching to 4.10s? If I can't find a 3.55 front I might go that route anyways.

 

[Thewespaul]

What trans do you have? How much do you tow? Turbo?

 

[JAKRANCH]

Diesel zf5. 10-12000 maybe 15000 lbs. If I'm towing there's significant grades involved. Turbo in my garage waiting to be installed

 

[towcat]

4.10's are your friend. night and day difference especially when adding a turbo and IC.

 

[IDIBRONCO]

The 3.55 gears work fine if you're towing light, and/or it's fairly flat. Since you have neither, I'd definitely switch to the 4.10 gears. You'll have more boost at your driving speed with the higher rpm's and probably lower EGT's as well.

 

[Shadetreemechanic]

I tow heavy (10-15K) pretty frequently with 33's and 3.55s. I do have a turbo. Only issue I have is getting a big load started on a hill, but the transfer case is always there if I need it.
I rarely tow like that in 5th gear. Fourth with 3.55 is almost the exact same final drive as 4.10s in 5th gear.
I have thought about changing gears, but I have 4.10s in a couple of other na trucks and I really like the way the 3.55s perform unloaded on interstate. I don't want to give that up.

 

[Hydro-idi]

You are going to want 4:10’s with those 33 tires.
Just regeared my Jeep that I bought with 33’s and a 3:55 ratio. It kind of sucked to say the least. Seemed like the engine was always lugging around town. Just had it regeared to 4:10’s and it was a night n day difference. Well worth the $

 

[jwalterus]

I tow some decent weight with my truck, N/A and 3.55s, my tires measure out to 33x11.25.
But I'm up in North Central ND, I can plan my trip around the couple of decent grades we have around here.
There's an old joke about the kind of landscape we have up here: "You can watch your dog run away for 3 days...."
Different mindset here, but I don't consider 10-15k an overly heavy load....... Even though it's more than these trucks were actually designed for.......
My 4th clutch in 7 years does not consider me a friend sometimes...............

 

[JAKRANCH]

@Shadetreemechanic nailed my struggle. I got 20mpg on my last tank highway driving. Half of that was a headwind and all of it had a four wheeler on back with the passenger seat thing causing extra drag. I wasn't going easy on the throttle either. Ya I don't consider this heavy either. My idi is for light stuff. 16 ft gooseneck trailer with 5 horses is what I'd be at max. I usually have one horse or a couple cows. Pulled a 30 foot full of yearlings once. On a flat road, 7.3 n/a 4.10s bone stock....featherlite is a lie!

 

[Shadetreemechanic]

If I ever have to get into my zf I will definitely grab the lower first gear out of the later model s47 transmissions. Otherwise I choose my gears to keep my rpms up. That means running 65 in fourth gear down the interstate. It tows great there, but falls flat on its face if I move to 5th.
I probably run lots of grades in 3rd gear that others would run in fourth.
I think for some folks they want there trucks to be able to climb all hills in high gear. I don't worry about that at all with my gearing, but I do get 20 unloaded as well.

 

[Thewespaul]

I like being able to cruise control at 80 with 2400 rpms so 3.55s and zf is my preferred setup. If you’re building a tow pig I would consider 4.10s or lower

 

[austin92]

I built a 10.25 for my 83. I went with 3.73 and a Detroit Truetrac. I’m very happy with the diff, gears are good for dd, but every time I hook to a trailer I wish I would’ve went 4.10. That’s on stock tires. 33s hands down 4.10


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[JAKRANCH]

Hmmm it sounds like the real answer here is to leave my truck alone....and talk the wifey into building another into a tow rig

 

[Thewespaul]

That’s always the answer, more trucks.

 

[Danielle]

That’s always the answer, more trucks.

I agree. My argument over the dinner table is we can always raise the max truck ceiling [emoji23][emoji23]

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