Basically, I am trying to find out once and for all what is the best gear ratio to use with 285s. I have seen conflicting info on this topic from various gear calculators/tables on the internet, Dodge Ram forums like this, and my local 4x4 shops. Given what it costs to change the gears, I want to make sure I get it right the first time. I have a '99 Ram 1500, 4x4, 5.2 with the stock 3.55 gears that were intended to go with 245's (30.47 inches) tires. I currently have 265's (31.65 inches) and would like bump it up to 285's (32.83 inches), but it is already a little sluggish on the low end with the 265's. I am a little concerned about gas mileage, I still want to be able to cruise down the highway at 65 or 70, and I tow occasionally in the summer time (small camper). So, in the end, my main goal is to increase low end performance through changing the gears (not engine mods), but still maintain decent gas mileage (doesn't have to be great gas mileage).

So, here is my main question:

Anybody running 285's with:
A) stock 3.55 gears
B) 3.92 gears
C) 4.10 gears

If A, is it sluggish, and how is your gas mileage?
If B or C, how do you like it compared to stock, and how did your gas mileage change?

Thanks all.

 

I had 3.55's with my 285's when I first go my truck and it was definately sluggish. I started doing some mods to it (air intake and hypertech) and it was much better. I eventually swapped in the 4.11's and its awesome now. gas milage was around 12 avg back then and it's been as high as 14.5, currently its down around 11.8 due to a bad plenum gasket and failed o2 sensors.

my suggestion... 4.11's all the way you'll be real happy with them.

 

Thanks steve00ram360.

Anyone else have an opinion/experience on this?

 

I dont have any suggjestions cause i know little to nothing about gearing. But i do have some ?'s cause i was thinking about 285's but i dont find the performance on the truck with 265's bad now....not a sports car but its not supposed to be. What i dont understand is that what exactly do the number mean ex: 3.55,4.10 etcc...and i thought that if a car/truck was geared for performance in general it LOST gas millage..any thoughts?

 

The numbers represent the gear ratio (4.10 to 1, or 4.10:1).
Say for example you have a gear ratio of 1:1. For every 1 turn of one gear, you get 1 turn out of the other. If a differential is said to have 4.10 gears (4.10:1 ratio), then that means that for every 4.10 turns you put into one gear, you get 1 turn out of the other, but with 4.10 times as much torque (hence why your low end performance will increase). Mechanically, it means that with 4.10 gears, the pinion gear turns 4.10 times for every 1 turn of the ring gear.

Yes, usually changing to lower gears (numerically higher number) negatively impacts your gas mileage, but mostly at higher speeds and rpm because they increase the rpm of your engine at increasing speeds (and probably a little because you might put you foot into it more when your off the line acceleration is improved).

Hope that answers your questions.

 

i have an 01 w/ 318 and 3.55's and am currently running 285's.
yes my truck in sluggish and mpg is 11 tops.i too am considering the gear swap.