Rear gear ratio suggestion?

[2k5Squirrel]

4.88's, that would make it geared the same as my brother's 4.8 ECSB, which has 4.56's with 31" tires. That thing is geared perfectly for a 4.8, imo.

Mileage? How much city/highway driving? 4.88 is what I'm leaning towards.

[CHEVROLADE]

456s worked real good when i had the 4.8 on 22s 31" tall

[screaminchicken]

My 4.10's on a 30 inch tire actually improved city mileage and didnt affect highway any measurable amount.

[Beatdown Z]

My brother does about 90% city driving. I did get a chance to log fuel mileage on the highway one time, and it was around 15. Take into consideration the truck has 200k miles, weighed down with tools, ladder racks with 2-3 ladders...

The nice thing about a properly geared 4.8 is how it is closer to being in the powerband during highway driving. Less downshifting and easier to maintain speed.

[mrfister]

Those are awful big #'s. What are the highway (80+) rpm's like? I did a 3.73:1 on mine, and it did leave me wanting more.

[1slo4.8]

My 4.10's on a 30 inch tire actually improved city mileage and didnt affect highway any measurable amount.

I had this same exsperience. I had 285/60/18 which is like a 31 I think and it actually improved my mpg when I swapped to 4.10

[2k5Squirrel]

My 4.10's on a 30 inch tire actually improved city mileage and didnt affect highway any measurable amount.

Same boat as you in my old 06 RCSB(in Sig pic). But in my new truck I do much more highway. It's between 4.30 and 4.56, I think 4.88 will be too much gear for me personally. I don't plan on more lift/bigger tires.

[pl4yboy]

You know, I'm probably going to do 4.10s in mine at some point. I get the best hwy mileage at 77mph. Anything less and it seems like its too low of an RPM. In city, I get terrible mileage with this stall and being so heavy. It takes a lot to get this truck moving. 3.42s just don't cut it.

[2k5Squirrel]

You know, I'm probably going to do 4.10s in mine at some point. I get the best hwy mileage at 77mph. Anything less and it seems like its too low of an RPM. In city, I get terrible mileage with this stall and being so heavy. It takes a lot to get this truck moving. 3.42s just don't cut it.

What size tire are you running? Do 4.30s! I don't think your highway would suffer and should really help your city. Check my "$$ gear install" thread, someone posted a link to calculate your cruising RPMs.


http://www.ls1truck.com/forums/power...rth-money.html

[pl4yboy]

What size tire are you running? Do 4.30s! I don't think your highway would suffer and should really help your city. Check my "$$ gear install" thread, someone posted a link to calculate your cruising RPMs.


http://www.ls1truck.com/forums/power...rth-money.html

Stock tires. 264/70/18. They don't make 4.30s for the front dif.