Gearing for best city mpg

[Corie1032]

Hello all, I have a 1998 4x4 4.0 ranger and it has 32's on it so it is lifted a bit. I have stock gears and was wondering if i should leave them be or change them? I do more city cruising than highway and want to know what the best gearing is for city driving. Thanks!

 

[Dirtman]

City driving can use lower gears and still get good mpgs, depends on what gears you have now, what the oem tire size was, and how the truck is working now. There's no magic answer. If it feels sluggish lower gears wont hurt, if it's still taking off from a stop good and getting good mpgs leave it alone.

 

[Corie1032]

City driving can use lower gears and still get good mpgs, depends on what gears you have now, what the oem tire size was, and how the truck is working now. There's no magic answer. If it feels sluggish lower gears wont hurt, if it's still taking off from a stop good and getting good mpgs leave it alone.

Thanks for the advice, would 3.73 be low gears? It seems good on acceleration, just want to make sure its not stressing out the tranny or engine when im driving with the bigger tires.

 

[Dirtman]

If you have an automatic you probably already have 3.73 or 4.10s. Those are pretty common stock gears in the autos. And you're not hurting anything with only 32" tires.

 

[RonD]

Welcome to TRS

Look on drivers door label to get current axle ratio, seen here: https://therangerstation.com/tech_library/axle_codes.shtml
Also get stock tire size, from same label

Then go here to see what larger tires did to ratio: https://therangerstation.com/tech_library/Gear_Tire_RatioChange.shtml

If for example your stock tires were 29" and new tires are 32" then a 3.73 ratio would now "act like" a 3.38 ratio
If you look on the Right at NEW, 4.12, that means a 4.10 rear axle would "act like" a 3.73 with 32" tires

The lower the ratio the lower the RPMs are at the same speed
But the lower the torque applied is as well

Higher ratio is better for towing or stop and go driving because it applies torque better at lower RPMs, for city driving

Larger tires have a triple whammy effect on MPG in city driving because they are heavier, they raise vehicle higher and they lower the axle ratio

On the highway the lower axle ratio is better(lower RPMs at 70mph), but heavier tires and high stance lowers MPG