37s on pickups

Salty4Life

Salty4Life

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Pathfinder III

2,307
Loxahatchee, FL, USA
First Name
John
Last Name
Larsen
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17415

I’m wanting to make the jump to 37s after I regear to 4.10. How do those running 37s carry a spare? The Baja style chase rack with two tires in the bed isn’t really practical for my needs.
 
Have you thought about a roof rack or standard tailgate replacement carrier?
 
I welded a 2 tire, swing out carrier 35 years ago for my F250. It also pinned to the tailgate when the tailgate was down...
this was with the stock 235/85R16s. I'm not sure why everyone buys everything.

F250 CC.jpeg
 
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Something to consider when Overlanding is the ability to purchase another tire, should you cut the side wall. Now you are out there with no spare, and finding another 37" tire will be much more difficult than a 35" tire, depending on where you are.
 
Wile_Coyote said:
Something to consider when Overlanding is the ability to purchase another tire, should you cut the side wall. Now you are out there with no spare, and finding another 37" tire will be much more difficult than a 35" tire, depending on where you are.
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He will has a spare and sounds like possibly two based on his question
 
Right on the spare, I get that. However, as some in the Military would say; two is one and one is none. Having two spare 37" tires would be more ideal, based on just how difficult it would be to get another one, when out in the sticks. But, if money and time is no object, they could wait to have one shipped in on the next truck or two.
 
No kidding on the weight. I used to have 37" MTR tires on my '99 4Runner.

70.JPG



Those things are heavy. I can't imaging trying to get one of those off the roof of a vehicle. Not to mention, having that much weight up high, throws off your ability to side walk any trails. Actually any weight up high is no bueno for trail running.
 
Is 4.10 going to be enough gear? For 37's I would think 5.13's or more. I'm running 4.10's with 32+ and it's the sweet spot for my v6 truck.
 
Without knowing the model of the truck, or how many gears the transmission has, or the transfer case, it's really hard to determine if 4.10 would be good enough for 37" tires. If just driving around, I would think yes. But, when a rig is under load (gear in the truck or towing), then that is when careful gear selection comes into play.

I drive a Silverado, so I made a chart to help figure out gearing relative to tire size:

Tire Size / Gear Selector


hmmm, seems I need to fix something on the chart. It's been a few years since I messed with the chart. And, I can see somebody else is currently using the chart. If you see the numbers changing, somebody is plugging in the numbers...

Google thing

Ok, I think I got it fixed and working properly.
 
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Docrandy said:
4.10s are more than enough for 37s
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I think about 90% of off roaders would disagree. Most current gen trucks with 37's run a 5 series gear, especially the Jeep and TRD crowd. With the new 8 and 10 speed trannies with double or triple overdrive you do not take a mileage hit like the old school rigs. My in town mileage picked up 2 mpg going from 3.42 to 4.10, the hiway mileage dropped 2 mpg. The increase in low speed off road ability more than made up for any added costs.
 
madcratebuilder said:
I think about 90% of off roaders would disagree. Most current gen trucks with 37's run a 5 series gear, especially the Jeep and TRD crowd. With the new 8 and 10 speed trannies with double or triple overdrive you do not take a mileage hit like the old school rigs. My in town mileage picked up 2 mpg going from 3.42 to 4.10, the hiway mileage dropped 2 mpg. The increase in low speed off road ability more than made up for any added costs.
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that might be true in the smaller trucks like you seem to have and have mentioned however with the transmissions on the full size trucks and especially the 2500 and up trucks like this sub forum is for that is not the case and 4.10s are just fine for most applications with 37s!
 
I dunno about that. there is general standard of power to weight ratio. I say general, as some vehicles such as the older Toyota 3.4 engines can be supercharged giving more power to weight than standard. But, most of our Full size rigs are well north of 6k pounds, with the 2500 rigs running over 7k pounds. That is a lot of weight to move, much less any gear that is in the truck. I would agree, that 4.10 is fine for tooling about town and occasional trail running, but in the long run, if you want to tow anything with a full size rig (as most full size rigs are designed to tow something large), I think the OP would be running into difficulty with 37" tires and 4.10 gears.

Just my personal opinion on it, nothing more.
 
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madcratebuilder said:
I think about 90% of off roaders would disagree. Most current gen trucks with 37's run a 5 series gear, especially the Jeep and TRD crowd. With the new 8 and 10 speed trannies with double or triple overdrive you do not take a mileage hit like the old school rigs. My in town mileage picked up 2 mpg going from 3.42 to 4.10, the hiway mileage dropped 2 mpg. The increase in low speed off road ability more than made up for any added costs.
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4.10s are definitely low enough for a heavy duty diesel with a 3 grand red line. Jeeps and Toyota’s probably would need lower gears because they have small motors, small trans, and small axles. Also the gas engines won’t mind the higher engine speeds. The truck came with ~34s and 3.42 gears stock, so 37s and 4.10s is going to be pretty close to stock.
 
ohhh, it's a torque monster. Why even ask about gearing?

Something else regarding your truck, if it came with 34" tires, those are definitely not stock tires. The largest tire the Ram trucks install on your 2018 model year are the 285/60R20, which equates to 33.5. You're already starting off under-geared for the truck's stated specifications.


Given that you have a large diesel engine, why re-gear, as you have stated in your first post?
 
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