Are 37s Practical?

[R.J.]

Considering doing a Carli level and also some wheels and tires. I think 37s look great but am worried overloading the drivetrain, ability to tow (not full capacity), not being able to carry a spare. I mean 35s make the most sense, but does anyone here run 37s on a daily driver?

 

[johanh13]

Considering doing a Carli level and also some wheels and tires. I think 37s look great but am worried overloading the drivetrain, ability to tow (not full capacity), not being able to carry a spare. I mean 35s make the most sense, but does anyone here run 37s on a daily driver?

I am considering the same and have similar questions! For me it has to be practical; I use my truck everyday and need it to be able to tow and be reliable. Also, I really dislike rubbing of any kind...

 

[elephantrider]

you need 4.10 or 4.30 gears when going to 37's. it takes the strain and leverage off the trans.

what is your day to day? do you tow often? pull a 5ver? lots to consider when asking what is practical.

 

[johanh13]

you need 4.10 or 4.30 gears when going to 37's. it takes the strain and leverage off the trans.

what is your day to day? do you tow often? pull a 5ver? lots to consider when asking what is practical.

I tow a bumper pull 14k trailer and a 26k (rated) gooseneck trailer, several times a month... I would love to see a 4.10 factory option on the SO Cummins... and an e-locker, at least for the rear

 

[Marshfly]

The factory 2019 gearing with 37s is almost exactly the same end gearing and the old stock trucks with stock tires and gearing. I had zero issue pulling my 11000# fiver with stock 3.73s and 37s, even over steep Rocky Mountain passes at altitude. When I moved to a 5th wheel with a 16800# GVWR I moved down to 34s. That much weight affected the mileage too much with the 37s. But even then, the transmission temps never got over the 170s.

Anyway, if you want 37s and don't tow heavy, just do it. There is no reason to regear if you don't tow more than about 10k.

 

[elephantrider]

the reason to regear is to take the stress off of the trans and to move the leverage to the rear axle. does it work and do tons of folks do it without a regear? yes. it it the appropriate way to do it? not necessarily.

 

[Marshfly]

the reason to regear is to take the stress off of the trans and to move the leverage to the rear axle. does it work and do tons of folks do it without a regear? yes. it it the appropriate way to do it? not necessarily.

Have you driven a 4th gen or 4.5 gen on 37s? I had them on my 2014 and on my 2019 pulling all kinds of loads. With anything under 11k, my truck would still pull most hills at low altitudes in 6th and only rarely downshifted to 4th at altitude on the interstate in the Rockies. Again, zero difference in trans temp between stock tires and 37s.


Regearing is certainly better but definitely not needed. Especially since the exact same truck only came with 3.42s last year. BTW, AEV uses 4.10s in their trucks with 37s and Ram will factory warranty that combo.

 

[elephantrider]

yes, I've had a 1st gen, 3rd gen, and 4th gen on 37's.

 

[Brutal_HO]

I don't know what size tires came on the 3.42 geared trucks, but here's some food for thought.

 

[Marshfly]

I don't know what size tires came on the 3.42 geared trucks, but here's some food for thought.

View attachment 5524

Same size since at least 2014. Stock 20s with 3.42s is almost the exact same effective ratio as 37s on 3.73s. The only difference is the 37s weigh about 25# more per tire.

My 37s were pulled off my 2014 the day before I traded and put on my 2019 within the first week. The difference in power was surprising. Both trucks stock gears.


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[Beranimus]

Running 37's on SO Cummins. Towed over 19k. Did fine. Daily it too. Love the 37's

 

[tienckb]

I got the HO and considering the same. What sez ya?


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[johanh13]

Running 37's on SO Cummins. Towed over 19k. Did fine. Daily it too. Love the 37's

Got any photos? I tow a 32' 26k gooseneck occasionally and a 20' 14K utility frequently... I want to go either 35" or 37" on 17x8.5" aev katla wheels, with minimal lift (if any)...

 

[g00fy]

Running 37's on SO Cummins. Towed over 19k. Did fine. Daily it too. Love the 37's

Would you mind detailing what's involved (if anything) to get those 37's under there without any rubbing? I've got a set of 17" Wheels off a 2013 power wagon, and I'd like to slap a set of 37's on them for my 2019 SO Cummins. Also, Pics Please

 

[jsalbre]

Everyone seems to be talking 37s on the Cummins. What about 37s on the Hemi? I’ve got 4.10s, so certainly in a better place than with 3.73s.

I only tow about 8000#, so nowhere near capacity.

 

[Beranimus]

Would you mind detailing what's involved (if anything) to get those 37's under there without any rubbing? I've got a set of 17" Wheels off a 2013 power wagon, and I'd like to slap a set of 37's on them for my 2019 SO Cummins. Also, Pics Please

Mine is a 2019 Ram 3500 crew cab long bed. Running a ReadyLift 3" leveling kit. There was very minor inner fender cutting on the front fenders. Carli suspension has a great video on youtube detailing where to cut. No rubbing at all with 20x9 0 offset and 37x12.5 tires.

 

[Beranimus]

Everyone seems to be talking 37s on the Cummins. What about 37s on the Hemi? I’ve got 4.10s, so certainly in a better place than with 3.73s.

I only tow about 8000#, so nowhere near capacity.

I'm not against the he I by any means and I'm sure it would have the power to run 37s but if it was me I'd probably stick with 35s on a gas engine.

 

[jsalbre]

I'm not against the he I by any means and I'm sure it would have the power to run 37s but if it was me I'd probably stick with 35s on a gas engine.

Circling back around to this, I was messing with my gear calculator spreadsheet and the Hemi with 4.10s and 37s is only turning 80 less RPM in 3rd at 50 MPH than with 3.73s and the stock 33s.

I’ve not seen many complain about towing with the 3.73s and that’s a pretty minor RPM loss. You’d have some loss of power due to heavier tires of course, at somewhere near 20# higher a corner for a 37x12.5Rwhatever vs the stock 285/60R20 Transforce A/Ts. Might be able to offset that quite a bit by moving down to smaller and lighter wheels though.

 

[blackwellbpb]

Circling back around to this, I was messing with my gear calculator spreadsheet and the Hemi with 4.10s and 37s is only turning 80 less RPM in 3rd at 50 MPH than with 3.73s and the stock 33s.

I’ve not seen many complain about towing with the 3.73s and that’s a pretty minor RPM loss. You’d have some loss of power due to heavier tires of course, at somewhere near 20# higher a corner for a 37x12.5Rwhatever vs the stock 285/60R20 Transforce A/Ts. Might be able to offset that quite a bit by moving down to smaller and lighter wheels though.

Did you end up doing 37s? If so how dpes it tow?

 

[jsalbre]

Did you end up doing 37s? If so how dpes it tow?

I never did. We’re actually selling the trailer this week and trying to get a house. Once I do that the truck will get traded for something smaller.

I love the truck but it doesn’t make sense as a daily driver without anything to tow.