4.10's or 3.73's for best mpg with 235-75-R15 tires?


koda6966

koda6966

15+ Year Member

Joined
Nov 28, 2007
Messages
7,898
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3,101
City
The green part of NY.
Vehicle Year
1988
Transmission
Automatic
I found a guy locally who has a Ranger axle, code 87. IIRC that's a 7.5 with 4.10's. My question is would I get the best mpg with these, or with an axle with 3.73's? I can always keep looking if I'd be better off with the 3.73's.

I also run 225-75-R16 tires in winter, if that makes a difference.
 
Whats your normal driving conditions? If you spend a lot of time with the speedometer at 70mph or more I would stick with 3.73:1 gears. If your driving consists of city traffic and 55-60mph I would throw in the 4.10:1 axle. Remember, if you install the 4.10:1 axle, you're still perfectly capable of exceeding 60mph, but your going to be feeding that engine slightly more fuel. Plus, the 3.0L loves the 4.10:1 gearing, especially if you have the 5 speed.
 
It's going to be all hilly highway mostly. 40-60mph. Usually around 55. This will happen for about 60 miles a day, 5 days a week. You can see why I'm looking to change from my stock gears meant for 215-60-R14ish tires.

I am however going to be on the interstate occasionally, so 65-70 there. Maybe once a week. So it's not all that important.

And I have auto.
 
I run 235/75/15s on my 3.0 4wd 5 speed w/ 4.10s.
Would never go any higher.
It came stock with 245/75/16.
Didn't like that combination near as much as this (equivalent to 4.33).
 
4.10's are "Good" on a 2wd with reasonably sized (225/70-15) tires

on a 4x4 I'd think seriously about even bigger gears...

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Last edited:
So 4.10s then? Gears confuse the hell out of me.

The guy wanted 180 for the Axle, I told him no. I can get them cheaper at the junkyard it just takes a while to find what I'm looking for. I'll have to be sure to check the gears and everything, but the yard I go to usually guarantees their parts for a return in one month of just the price of the part, fees not included.
 
I'm running 29x8.5r15 TSL's with 3.73's and it's OK. It's noticeably slower than when I was running 225/75r15's, but nothing a little extra go-pedal won't cure. My fuel economy hasn't changed much (if at all) since switching to the slightly narrower, taller and heavier tires. 4.10's and a locker would sure be nice though...
 
at one point i had 2 nearly identical trucks (87 super cab, 2.9) the only difference being the gears. one truck had 3.73's and the other had 4.10's. the truck with the 4.10's was noticeably peppier, and gave me 2-3 mpg better than the truck with the 3.73's. i suppose there could have been another issue with one of the trucks that i wasn't aware of, but i would certainly go with the 4.10's.
 
koda6966 said:
So 4.10s then? Gears confuse the hell out of me.

The guy wanted 180 for the Axle, I told him no. I can get them cheaper at the junkyard it just takes a while to find what I'm looking for. I'll have to be sure to check the gears and everything, but the yard I go to usually guarantees their parts for a return in one month of just the price of the part, fees not included.
Click to expand...

4.10's are better than what you have but you may find that
4.10's aren't enough.

My 2.9 was also "Very happy" with 4.10's and 235/75-15's
a 3.0 is a revvier engine and with those taller tires 4.10's
may not be enough...

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