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question about tires and gearing

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by huntinfool79, Jan 13, 2006.

  1. huntinfool79

    huntinfool79 Registered Member

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    I want to run either 35's or 37's on my 72' but wonder if a dana 44 and a 12 bolt will handle 37's and what is the best gears to run with these tires I have heard 4:56 and others have said 4:88 gears what do you guys recomend
     
  2. lamberthkp

    lamberthkp SITFU Premium Member

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    id say 4.56 was fine in mine but i still had a OD tranny because its a DD. as far as the D44 and 12 bolt they would be ok but, how much offroading you do? light to medium offroad n would probobly b ok. but a 12bolt is recomended for no bigger than 35's . i had 38 on my 12bolt when i tore all to pieces now i'm stuck with a 10bolt until i find 1ton axles. depending on how hard you wheel i would say upgrad to 3/4 to 1ton axles.
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    If you plan to run it on the highway a lot, you'd be smart to calculate the cruising RPMs you are willing to turn (Big blocks are usually around 2100 - 2300 RPM, small blocks can spin higher...maybe 2300-2500RPM) then pick the final gearing based on whichever one gives you the correct numbers.

    Most people put the deepest gears they can find...and then get all grouchy when the truck won't run down the highway at a reasonable speed anymore.


    It's probably a waste of money to re-gear your existing axles, unless the 37s are just "for show" :wink1: If you actually want to wheel it, you are probably better off doing an axle swap to at least a 3/4-ton setup (8-Lug D44 & 14BFF) or go all the way to a 1-Ton setup (Dana60 / 14BFF)

    :usaflag:
     
  4. Burt4x4

    Burt4x4 3/4 ton status

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    Ya I wouldn't run bigger than 35 on your 44/12 setup. But if all you do is goto the mall in it then you be ok hehehehee

    If I was starting from scratch I would do axels & drivetrain first (upgrade as close to 1Ton as your wallet will alow) then get the tires & wheels you desire/need for the type of wheeling you want to do.
     
  5. mr_blasto

    mr_blasto 1/2 ton status

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    The general consensus is that 1/2 stuff is ok for 35". Some people are very careful and get away going bigger than that without breaking too much. As a rule of thumb, if you plan on ever going bigger than 35 geat 3/4 or 1 ton axles. It has also been said that 35" tires with a 12 bolt have the same (if not more) ground clearance as 37" tires with a 14bff. Some food for thought.

    As for gear ratios... if the tires is a true 35 inches, going with 4.56 gears will be very similar to running stock tires with 3.73's. I personally have tires that measure just under 35 inches and I opted to go with 4.88's (getting installed next weekend), but I also plan on going with an overdrive transmission in the not so distant future.

    As mentioned it is a matter of personal taste, type of driving, and driving style
     
  6. 70chevybob

    70chevybob Registered Member

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    Well, From personal experiance I ran 37" boggers and a dana 44/12bolt for over 4 years. I Wheeled the hell out of it and only broke U-jounts from NAPA. and a few Wheel joints. I was running a SM465 205 and 3.07 gears. I could run a 4 rated trail with finesse. Frineds with dana 60's would use the go pedal and break more than I did.
    This was my daily driver too and I could go 70mph down the HW without running 4000 rpm.
    I have upgraded and have locked dana 60's w/4.56 gears and now I push my rig harder and break more than I used to.

    It all depends what type of driving that you are going to be doing. Now My old daily driver sits in the Shop untill it is loaded on a trailer.
     
  7. vtblazer

    vtblazer 1/2 ton status GMOTM Winner

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    What about staying with a 1/2 ton set up but upgrading the axles?
    Will other stuff begin to break?
    You could maybe go 37's/38's and get decent/good ground clearance.

    Edit: Did some of my own research here.
    You may as well spend the $$$ and get everything the 3/4 or 1 ton axles have to offer. It'd be cash better spent.

    My D60 w/37's drags all the time. :doah:
     
    Last edited: Jan 14, 2006

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