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  1. #1

    Question Is anybody running 4.56s with 37s??

    I have 4.56s and Im wantin to go up to 37s, is this gona kill my power and mpgs?
    If you have that setup, or even if your running 36s, how do you like your power and mpgs?

  2. #2


    I have 4.56s in my Suburban. Had 35's and that worked good. Installed 37's and broke a rear axle first time out, plus the truck just didn't have the bottom end. It felt like driving a truck with stock 30" tires and 3.42 gears. 1/2 ton truck axles really don't like anything over 35" tire. With 37's you would want a 4.88 gear set, but the 4.88's break easy on these 1/2 axles because in order to get all the teeth machined to make up a 4.88 gear the teeth on the small ring and pinion they have to be thin so they break easy. I would keep the 4.56s with 35's.

  3. #3


    Quote Originally Posted by silveradotrailblazer View Post
    I have 4.56s in my Suburban. Had 35's and that worked good. Installed 37's and broke a rear axle first time out!
    so u wheel this thing? mine is for highway use, and I am running ab 3,000 rpm at 80 mph... I dont like runnimg that high rpm! think it will work on a non wheeled daily driver?

  4. #4


    Do you have your truck programmed at all? That is really high rpm's. I don't have 4.56's, I have 4.10's with 37's and I am running at 2,000 rpm's at 70. I would try to get your truck programmed so that your computer (ECU) will know your running on a certain tire size. Just my two cents....
    "You underestimate my willingness to resort to violence to resolve this conflict" :fighting0037:

    2006 Chevy Silverado 2500 HD LT
    (8" Fabtech Suspension Lift, 3" Performance Accessories Body Lift, 37x13.50 Toyo MT's, 20" KMC Rockstar, K&N FIPK, Edelbrock Headers, Edelbrock Extreme Travel Shocks with Reservoir, MagnaFlow Dual Exhaust, Black Bear Performance Tune)

  5. #5


    Yes LivysMan I do wheel the Burb. If you don't go off-road to much you may be O.K. with the 37's. You will wear out axles and CV joints quicker.They do seem to take alot more power to get the truck moving.

  6. #6


    Land Shark, Yes I have a SuperChips Flashpaq with the correct tire, gear size programed
    But see you have: higher gears, taller tires, and lower speed! 3 reasons for your RPM to be lots lower than mine! How is your RPM, MPG, and power??

    silveradotrailblazer, Yea all that is stuff to think about... I found some 36x15.50x18 Mickey Thompson MTZs I wonder how good they would do? I love these Grapplers, but they dont make a 36x18.. I just really love the 37-38 look!! guess I need to go ahead n break down n get a SAS!! lol thats what I really want!!

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