3.55's or 3.31's???

superstroked · Aug 17, 2011

08stroker250 said:
Nope, not towing. Just don't want to drive a car. I have driven a truck since I was 16 years old. If I can make my truck better on fuel with a simple gear swap, I'll do that way before going to a little ass car. 600 HP truck and 22-25 MPG on the highway vs. 200 HP car and get 35 MPG on the highway. Pretty easy decision for me.

more like 100 hp and 160ft lbs HAHA that would get 40+ on the highway.. good luck with the numbers you are trying to achieve but, I don't see it happening

Mpoage · Aug 17, 2011

How many miles does your truck have on it?

Jeff@Spartan · Aug 17, 2011

superstroked said:
more like 100 hp and 160ft lbs HAHA that would get 40+ on the highway.. good luck with the numbers you are trying to achieve but, I don't see it happening

So you don't think a 400-500 RPM drop on the highway would result in better fuel mileage? Boost would be lower, fuel output would be lower, RPM's would be lower. That is keep (at least in my opinion) to achieve good fuel mileage in a truck. Mike Corsilli (Mike@MPD) claims to be able to get 22-23 in his truck on the highway with 3.55 gears.....I would be happy with that, and it shouldn't be a problem at all with 3.31 gears.

Mpoage said:
How many miles does your truck have on it?

Coming up on 118,000 miles.....quick!

superstroked · Aug 18, 2011

I have never gotten anywhere near that kind of mileage with my 3.55's. I don't drive for "hyper mileage" and generally run around 75-80 on the highway. The tires I have don't help my cause either( I lost about 1-1.5 from stock). The best I have seen since putting them on is about 14 or so. That being said, usually if I take a long highway only trip I have one of the trailers in tow. Otherwise We will take the equinox so, I am not sure what it would do unloaded on the highway between 70 and 75mph. Hope that helps.

In theory it should save you fuel mileage switching out your gears but, above 70 wind resistance really starts to comes into play. So with the gear ratio change in order to keep the rpm's in the sweet spot (between 1700 and 2000) what would that put your speed at? I am sure someone can calculate it. If it is around 80 at 1800/1900 rpms, it may be like pissing in the wind due to the wind resistance.

just some things to think about

Jeff@Spartan · Aug 18, 2011

If I am running 80 right now, I am at 2200-2250 RPM's. 75-80 MPH (usually 80 MPH) is my average speed on the highway. I am currently running 305/55/20 Toyo AT's, which don't help. They measure 32" on my wheels and are really, really heavy tires. The plan is to do 22" wheels and 305/45/22 Nitto 420's. If I were to keep my 3.73 gears and run those wheels and tires, my RPM's would be like 2300-2350 at 80 MPH, which would make my fuel mileage even worse. I believe the 3.31 gears to be appropriate for the direction I am headed. I have a few other things up my sleeve to improve fuel mileage, so we shall see. I think efficiency is key, and the mods I will do should really improve the efficiency of my motor.

superstroked · Aug 18, 2011

08stroker250 said:
If I am running 80 right now, I am at 2200-2250 RPM's. 75-80 MPH (usually 80 MPH) is my average speed on the highway. I am currently running 305/55/20 Toyo AT's, which don't help. They measure 32" on my wheels and are really, really heavy tires. The plan is to do 22" wheels and 305/45/22 Nitto 420's. If I were to keep my 3.73 gears and run those wheels and tires, my RPM's would be like 2300-2350 at 80 MPH, which would make my fuel mileage even worse. I believe the 3.31 gears to be appropriate for the direction I am headed. I have a few other things up my sleeve to improve fuel mileage, so we shall see. I think efficiency is key, and the mods I will do should really improve the efficiency of my motor.

good luck in your quest grasshopper...and please, post results! :toast:

apollyon9515 · Aug 18, 2011

Id try the 3.31 since you dont tow or pull anything. One way to possibly save money(maybe not the smartest) is to just regear the rear gear to test it out for a few months, that way if you dont like the 3.31 and want to switch you wont have to pay to regear two axles. Not sure if they sell just a front or rear gearset, but id imagine they do.

Also you said your not racing so you wouldnt need to do any 4x4 boosted launches and could maybe get by with just 2wd for a bit.

samoht517 · Aug 18, 2011

What about a gear vendors overdrive. That way you can get the good mileage of a taller gear but could still race or tow if needed.

Jeff@Spartan · Aug 21, 2011

Decided that 3.55's will probably be best with the tire/wheel combo I am going with. I am going to eventually do 22x9.5 BMF Stealth Novakane's with 305/45/22 Nitto 420's. I think 3.31's will be a little too tall of a gear for a 32" tall tire. Opinions?

SouthFlstrokin' · Aug 22, 2011

I think you'd be alright with 3.31s and a some 305/45r22 tires. With 3.55 you won't really notice a difference. Jmo

Jeff@Spartan · Aug 22, 2011

SouthFlstrokin' said:
I think you'd be alright with 3.31s and a some 305/45r22 tires. With 3.55 you won't really notice a difference. Jmo

My current tires are a hair over 32" on the ground and I have 3.73's. I think I will probably notice a difference....don't you?

SouthFlstrokin' · Aug 22, 2011

Your running 305/50r20s right? I was always under the impression those were 32s and the 305/45r22s were almost a 33. So with that in acct. I guess a 3.55 would be closer to a 3.31 anyways being its a taller tire.

Spatel23 · Aug 22, 2011

08stroker250 said:
Decided that 3.55's will probably be best with the tire/wheel combo I am going with. I am going to eventually do 22x9.5 BMF Stealth Novakane's with 305/45/22 Nitto 420's. I think 3.31's will be a little too tall of a gear for a 32" tall tire. Opinions?

have you played with the calculators at all?

SouthFlstrokin' · Aug 22, 2011

Spatel23 said:
have you played with the calculators at all?

Google that size tire, it shows 32.8". So figure its a 33.... Taller tire, taller the gear.....

Jeff@Spartan · Aug 22, 2011

SouthFlstrokin' said:
Your running 305/50r20s right? I was always under the impression those were 32s and the 305/45r22s were almost a 33. So with that in acct. I guess a 3.55 would be closer to a 3.31 anyways being its a taller tire.

I am running Toyo AT's right now. They are 305/55/20's which are supposed to be right at 33" tall, but mounted and on the ground, they are just over 32" tall. When I had Proxes on, I doubt they were even 31.5" tall mounted and on the ground. I am thinking the 305/45/22's will be right around 32" on the ground.

Spatel23 said:
have you played with the calculators at all?

Calculators don't work too well for that stuff, plus tires are shorter mounted and on the ground. I am guessing it will be about 31.8-32" on the wheel and on the ground.

Dave · Aug 22, 2011

08stroker250 said:
3.31's would obviously be the best for fuel mileage, but would they affect drivability? That is my concern. Hoping to hear from people who have driven with both.

3.31s are a non issue at your power level. Remember thats what the 2011s are coming with from the factory