Right now I have 3.55 gears with 285/70/17 size tires. My truck is slower to accelerate than before because of the new tires. Its not horrible, I can live with it. My big question is at some point I want to run 35 inch tires or maybe even larger. What gears should I run? I was thinking 4.10s.

 

just go 4.56's. There are a couple threads around discussing pros cons. Unless you drive a ton of highway, like at least 75%, I would def go 4.55's. There's one where hammer is very convincing in discussing 4.10's vs 4.56's. Ill go try to find it for you.

 

I couldn't find the thread I was thinking of exactly, but here's a copy paste of one of hammer's thought processes. If you are gonna run 35s i think i would go for the 4.56's

" When thinking about re-gearing there are two important things you have to think about. First is the fact that you have an automatic transmission that essentially has two over-drive gears, so numerically over-gearing is pretty hard to do. With 4.56s & 35" tires I only tach just slightly over 2000 rpm at 70 mph and the Hemi engine doesn't really even begin to reach into it's power curve until about 2200 rpm.

Secondly, you have to think more about effective gearing than the actual gears. Stock 3.55 gears only act like 3.55 gears with 31.5" tires, so even 33" tires have your gears down in the neighborhood of 3.3:1.

If you plan on staying at 33" for your tires then 3.92s wouldn't be a bad idea BUT 4.10s would give just a bit more bang while not using any more gas on the interstate than 3.92s or would be so close it would be just about immeasurable.

IMO 4.10s would be a perfect balance of power increase/less transmission work and MPGs on the highway. Of course 4.56s would be my choice if I towed/hauled much or if most of my driving was confined to in-town applications OR if a loss of 1-2 MPGs on the interstate doesn't bother you. Obviously, since you would have to give it less throttle to achieve acceleration from a dead stop, numerically higher gears actually help in-town driving MPGs..."


I think that sums it up pretty good.

 

If you can justify the cost, go for it. Make sure you research the shop. This is no job for wrench-pullers.

 

Since you have 3.55s you really can't go wrong with either 4.10s or 4.56s. I really comes down to what you want out of the truck. I do mostly in town driving but I'm also not willing to give up 1-2 mpgs on the highway for the 4.56s. I have 3.92s now so I can't justify the cost of regearing to 4.10s either so I stick with my 3.92s. But like ewing quoted if you can deal with the highway loss you can't beat 4.56s. But if you want a good balance then go with 4.10s. You'll feel the difference regardless since you have 3.55s now

 

So i have a third party opinion, about what cost should i be looking at for this job? What parts should the shop need so they don't try to overcharge me?

 

Price depends on the shop and drivetrain. For a 2WD it can range from about 700 to 1200 and for 4x4 from about 1500 to 2400. You'll want to find a shop that had done AAM 9.25 rear ends before because apparently our rear ends are tricky if you haven't done a couple before hand.

 

4.10s would be ideal with a four speed or manual tranny truck, but your 545rfe has basically two overdrive gears. Because of this, you can get away with 4.56s and still have very manageable rpms even at higher interstate speeds.

Go 4.56, I promise you if you go 4.10s you'll wish you went 4.56...

 

When i requested the build sheet from dodge it says that i have a four speed

Quote from build sheet "DGBS All 4-Speed Automatic Transmissions DGT 4-Spd. Automatic 46RE Transmission"

Another question would i save myself some money by doing a LSD, thinking the Detroit TruTrac, and gears at the same time.

Last question i promise. What are some good brands to look for in gears, I don't want to have gears that break in a year or so.

 

If you have the 5.9 360 then you have the 4 speed 46RE transmission. 4.10's would be great in that truck.