Ideal Highway RPM's and Gearing For 37s

boy&hisdogs

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now I need to find an accurate chart to know whats what.

burb has 3.73 and 30" tires. I know they are 3.9% larger/faster than stock.

Sierra has 3.43 and 28" tires...

I thought these set ups had me just slightly in the fuel economy side but now I have no idea.

Those are good all-around ratios for daily drivers. My truck originally had 3.42s with 32" tires, and 4x4, which adds rolling resistance as well as air resistance since the 4x4 rides a few inches taller than a 2wd. Even then it was fine 99% of the time just driving around.

What mpg are you getting from the pickup? if it's 15+ I'd say that's pretty good for these trucks.
 

PlayingWithTBI

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Here's a calculator where you can find your tire height and then calculate your "Optimum Rearend Ratio"
 

ameadows7

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Thank you for posting this, I’ve been searching what seems like forever for someone with a nv4500 that’s installed new gears in the axles. I was thinking 4.56 but looks like I’ll be buying 4.88.
Sure thing. Now debating between 5.13s and 5.38s for 40s when it gets a SAS but haven’t looked at a calculator yet. You will not regret 4.88s for 35s
From what I've noticed driving other people's built trucks and jeeps and now having my own gears done (4.88/37s), go as low as you can and still tolerate it on the highway. While driving around town I often think "I could have gone 5.13, that would have been nice" but on the highway I don't think I'd want to turn any more RPMs than I already am.
Exactly right and that’s why I chose the 4.88s for mine. I read a bunch of threads and looked at the calculators and decided they would fit my needs best. I commute, tow, and go off road with it and the gears are perfect for me. It had 3.73s and 35s when I first bought the truck and 5th gear was unusable
 

boy&hisdogs

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Sure thing. Now debating between 5.13s and 5.38s for 40s when it gets a SAS but haven’t looked at a calculator yet. You will not regret 4.88s for 35s

Exactly right and that’s why I chose the 4.88s for mine. I read a bunch of threads and looked at the calculators and decided they would fit my needs best. I commute, tow, and go off road with it and the gears are perfect for me. It had 3.73s and 35s when I first bought the truck and 5th gear was unusable

This is the one that I use. It has "too many" options for most people, but that's exactly why I like it. You can really play around with the settings to get exactly the specific information you need.

 

WOalmann

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Sure thing. Now debating between 5.13s and 5.38s for 40s when it gets a SAS but haven’t looked at a calculator yet. You will not regret 4.88s for 35s

Exactly right and that’s why I chose the 4.88s for mine. I read a bunch of threads and looked at the calculators and decided they would fit my needs best. I commute, tow, and go off road with it and the gears are perfect for me. It had 3.73s and 35s when I first bought the truck and 5th gear was unusable
That’s pretty much what I plan to do with mine as well. I have a 92 gmc Stepside regular cab. Before I installed the 6” suspension lift and 35’s. I dropped in a crate motor from Blueprint (5.7 350 small block with vortec heads and a mild cam). The dyno sheet they sent with it read 373 hp. I’m unsure of the stock gear ratio, the sticker in the dash is gone and I can’t find any tag on the axle itself, but it does have an NV4500. It runs through the gears decent doesn’t struggle and 5th gear is usable, but can certainly tell a difference between the 265’s and 35 inch tires. just want to be able to push some bigger tires around and not stress moving parts anymore that I have to.
 

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