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Gearing: 4.56, 4.88, or 5.13

Best Gear Ratio for 80% trail, 20% street on 37” tires

  • 4.56

    Votes: 0 0.0%

  • 4.88

    Votes: 6 19.4%

  • 5.13

    Votes: 25 80.6%
  • Total voters
    31
Big Ray said:
It may have been mentioned, but here's a cool rpm/ gear ratio/ speed calculator...

Clicky
Click to expand...

Thanks for the link! That is the calculator I’ve been messing around with. I really like how all the ratios are preloaded.
 
bablazer73 said:
I always lean on the aggressive side. 5.13's
ran them with 40's and 44's.
my daily was 35's with 4.10's, 350/700R4, and always thought it needed more....
Click to expand...
So if you have 37" you should be running 4.88 right?
Since 5.13 was good for 44"
 
Gibby56 said:
I have been playing with gear ratio calculators a ton but would love some real world feedback.

I am planning on going through the axles early next year and am starting to compile parts. Curious to hear what gears you guys are running in rigs that are primarily trail use. The K5 will be towed to the general area of the trails but will be driven to the trailhead. Last rig had 6.17’s and 41’s but not enough power to hit 5th gear. The Blazer has the extra 4 cylinders that one was missing.

Current Drivetrain: 350, 4L60 (700R4), NP241, D60/14BFF with 4.10’s, 37’s

Planning to stay 37’s on this one

What is your experience with any of these ratios? Any regrets?
Click to expand...
In case my post was not clear, the 4.88 were perfect with the th350 and I was wheeling moab with rarely touching the throttle except when front locker was not working.
The highway speeds were my problem so I put the 700r4 and now it's perfect.
If you go 5.13, you'll be wishing you have double overdrive
 
skunked said:
Depends on his expectations however I would be more than happy with 65mph @ 2100 rpms with the 5.13's.
Click to expand...
skunked said:
Depends on his expectations however I would be more than happy with 65mph @ 2100 rpms with the 5.13's.
Click to expand...
I need to do the math on that one but my th350 was at 3000 rpms at 65mph so I was not happy with that. The overdrive fixed that.
 
I voted 5.13, I have 5.38s and its perfect with 37s and a 700r4 and TBI 350. I have approx 60k on this drivetrain, works good.
 
Gibby56 said:
I have been playing with gear ratio calculators a ton but would love some real world feedback.

I am planning on going through the axles early next year and am starting to compile parts. Curious to hear what gears you guys are running in rigs that are primarily trail use. The K5 will be towed to the general area of the trails but will be driven to the trailhead. Last rig had 6.17’s and 41’s but not enough power to hit 5th gear. The Blazer has the extra 4 cylinders that one was missing.

Current Drivetrain: 350, 4L60 (700R4), NP241, D60/14BFF with 4.10’s, 37’s

Planning to stay 37’s on this one

What is your experience with any of these ratios? Any regrets?
Click to expand...

I'm glad you posted about this. I am collecting parts for axle rebuild/re-gear and have been debating the same thing for my rig with a NV4500/NP208 and 35s or 37s. Mine will be more like 70% road and 30% trail so I was leaning more towards 4.88s
 
I had 5.13’s and 39.5’s (measured to 38”) and ratio was perfect, couldnt have imagined having anything else and that was mostly hwy driving.

Also had 4.10’s and 42’s, and always drove on highway in 3rd (making OD pointless). Sold the truck before i swapped gears in that one.
 
I haven't used 4x4 in years and haven't changed the front gearing yet, but I have a 6" lift with 4.88 in the rear with tires just shy of 35" and a new stock 350 tbi and the 700r4. It is great around town and taking off from a stop......much better than the original 3.73 gear with those tires.

70-75 mph on the freeway is really working the engine with small grades and it will downshift to 3rd sometimes due to the amount of throttle. 65 mph is good and around 2400 rpm in overdrive.

For bigger tires and mostly offroad, I would go with 5.13.......just don't expect to haul ass on the freeway with a stock engine.
 
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