jbryant777

i have bone stock 2013 4.3L v6 4 speed auto rcsb with 275/55/20 which is right at at 32" tire with 20x9 wheels that id say were medium heavy. i definitely felt a weight increase after changing from stock 17s. tow light loads pretty often. 70% city driving, 30% hwy driving. stock gears are 3.23.

question: 3.73 or 3.90 or 4.10.

ive honestly been leaning toward 4.10 but dont want screaming highway rpms and even worse gas mileage than im already getting.

Also im thinking that the 3.73 would probably put me back at stock power with the 32's but i am wanting slightly better acceleration than when I had the stock 17's but IDK ??????????????

ALL opinions welcome please!!!

FFDP

iTrader: (2)

3.73's or 3.90's would be my pick. 70 mph is around 1800-1900 with my 3.73's, still pulls low 20's on the freeway.

jbryant777

alright, and anyone else?

DarkCharisma

Don't fear gear.

I'd look at 4.10's as the starting point, and consider going deeper. Your truck is working hard to move the weight + the wheels, having more gear and slightly higher RPM won't be nearly the trade-off you're thinking it might be.

jbryant777

you dont think i would lose alot of gas mileage with 4.10s? ive noticed 2-3 mpg drop since adding the 20x9s and 275/55/20s with the stock 3.23 gears. my main goal is getting slightly better acceleration with the 275/20/55 : 3.73 or 4.10 compared to the 245/70/17 : 3.23 gears that came stock while getting at least the same gas mileage as stock or better. why didnt i get an LS instead of the 4.3L . that would have probably solved all problems in itself.

jbryant777

also i know i can get oem 3.73s but do they make oem 4.10s? and ive read somewhere that the lowest gear i can swtich to is 3.73 with my stock rear end carrier? is this correct?

LS1TRUCKGUY

iTrader: (7)

That is incorrect. I ran a 33" tire with 410 gears and i thought about going to to 4:56s.

LS1TRUCKGUY

iTrader: (7)

I also ran a 29" tire with 4:10 gears in my rcsb and it was perfect. About 2200 rpm on the freeway and i picked up about 2mpg over stock

jbryant777

what were your highway rpms with this combination?

with me having a 4 speed trans and even with the OD, im thinking that my rpms would be really high during highway speeds...

LS1TRUCKGUY

iTrader: (7)

around 1800rpm at 70mph. with a v6, you need all the gear you can get. its all about mechanical advantage. yes you will be turning a few more rpm, but the engine is not working as hard. you fuel mileage will increase.