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How big of tires can I get without changing gear ratios?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by weisel, Mar 18, 2001.

  1. weisel

    weisel 1/2 ton status

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    I have a 77 k5 with a stock 400 engine, th350 automatic tranny, 203 (or however you say it) transfer case, and 3.73 gears. How big of tire can I go, but still being able to push it around, and not messing up my alrady horrible gas mialige? Now this has nothing to do with lifts and such, I'm just talking about if it has enough power.

    Insurred by Smith & Wesson
     
  2. bigerik

    bigerik 1/2 ton status

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    At one point I had 3.73s and 33" tires, and it did OK. No way I would go over 35s with a 3.73:1 ratio, even if you had a granny gear. Why don't you want to switch gears? Too much $$?
     
  3. wayne

    wayne 3/4 ton status

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    35 would be the max with 3.73 gears if you want it to still move pretty good.

    <A target="_blank" HREF=http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html>http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html</A>
    <font color=blue>Happy Trails[​IMG]</font color=blue>
    <font color=blue>Wayne</font color=blue>
     
  4. thatK30guy

    thatK30guy 1 ton status Premium Member

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    I had an 86 short bed K10 with 3.73's and 35's. That truck smoked those tires like no tomorrow. In fact, any ratio would work for any tire size. The thing I look at for tire spin is the strength of the motor. Anybody can get a 3.08 rear to smoke 44 inch tires as long as they had a peppy motor.
     
  5. CaptCrunch

    CaptCrunch 1/2 ton status

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    That would be one heck of a motor to do that w/ no granny gear [​IMG] ! But you are correct... depends on the power and torque of the motor as well as axle ratio... although freeway rpm also enters down the road and transmission gear ratios as well. A TH350 isn't anything special... But say you throw in a lower first gear ratio like a 700R4 has and that will really help off the line. We threw a steeper gear in my buddies TH400... all I can say is WOW[​IMG]!

    1987 Chevy K5 Blazer- 350 TBI
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I'm running 33's with 3.42's, truck has no problem moving out smartly. Not gonna win any drag races, but I have no problem hitting way over 60 on a freeway on-ramp.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  7. slider79blazer

    slider79blazer 1/2 ton status

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    I have a 79 blazer w/35" tires. It has the 400ci. engine
    350 tranny automatic with 3:73. I had 6.5 miles to the gal.
    before, then I put a K&N air filter kit on. Also new distributor
    cap and rotator. and headers w/ dual exhuast. I get between
    8-9 gals. now but I might get better if I wasn't a lead foot.It made a big differance in power.I'm going to put on a throttle body injection setup on soon.
    Let you know if it helps!!
     

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