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Tire Size + LOW RPMs

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by tecton, Nov 18, 2003.

  1. tecton

    tecton 1/2 ton status

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    45-55mph its at mabye 1100-1200rpm...

    this is due to 3.42 gears and 33inch tires...

    To regain some power...how prudent would be replacing the 33's with 31's but mabye try to find a super wide tire to maintain a stout look...

    31x12.5 perhaps? or even wider if its made

    Im looking at Micky Thompson Baja Belted and Baja Belted HP...31x12.5, and 31x13.5....anyone have any input on these tires...they look nice since im wanting to move out of mud to a more A/t tire

    also...any pics of a truck with these tires on them
    the size anyway
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    There is a 31x12.50 bogger,SSR,thornbird,and a 31x13.50 SX.
     
  3. tecton

    tecton 1/2 ton status

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    more of an at tire...

    remember, i want to upgrade as far as wear from MT's...so boggers are the last thing i need
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    45 mph, 3.42's and 33's in OD = 1096 rpm
    45 mph, 3.42's and 31's in OD = 1165 rpm

    Not enough of a difference to bother worrying about.

    Try this though:

    45 mph, 3.42's and 33's in D = 1566 rpm /forums/images/graemlins/thumb.gif

    Leave it out of OD unless you're on the freeway, or do a ratio change up to 4.10's at least.

    Rene
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I say you swap to 3/4 ton axles. They'll already have the gears you want (4.10) and you'll be able to pull your tires.

    Those mickeys are trash. They're not going to be quiet because they're bias. Even radial mud terrains are going to be a quieter tire.
     
  6. tecton

    tecton 1/2 ton status

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    3/4 ton axles weigh more

    i can barely go as fast as id like to now...

    i know the thing about not using OD...but, what is the D rpm with 31's
     
  7. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    With 33" rubber, 3.42 gears, and a 700R4:
    2050rpm in third gear at 60mph
    2550rpm in third gear at 70mph
    1550rpm in fourth gear at 60mph

    I can barely hold fourth gear at 60mph (usually leave it in third until I hit 65mph). At 70mph (1900rpm) I can hold fourth pretty easy. At 80mph I have to shift back into third.

    Bajas are really noisey. I'm not sure about wear.
     
  8. tecton

    tecton 1/2 ton status

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    what are safe cruising rpm's for a 350
     
  9. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    I a smallblock chevy will cruise all day long at 2800rpm. Although kinda hard on gas. I like to be 2400-2500 cruising at 70mph.

    John
     
  10. JK5

    JK5 1/2 ton status GMOTM Winner

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    I had a 79'k5 with 3.42's and 31x11.50x15 BFG AT's...
    The truck had good acceleration..
    and wasn't winding out on the highway...GOOD COMBO!!!! /forums/images/graemlins/thumb.gif

    My Black k5 has 33x12.50x15 SSR's...with 3.73's..
    it's about the same..
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    3/4 ton axles weigh more

    i can barely go as fast as id like to now...

    [/ QUOTE ]

    You sure would be able to go a hell of a lot faster if you had better gears and your engine wasn't lugging. Raising your cruise RPM to 2200-2500 would help you pull your truck down the road MUCH better.

    My 1 tons both cruised at 3,000 RPM or so at 65 their whole lives. That's how GM geared them because obviously a 1 ton is a pullin rig. With EFI, my '87 C30 actually gets 14 MPG empty which I'd say isn't bad at all.
     
  12. 99firehawk

    99firehawk 1/2 ton status

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    blown 355+3 speed+ 4:10s + 28 inch tire= 3800 @ 75 engine held up fine couldnt pass a gas station though.
     
  13. 75-K5

    75-K5 3/4 ton status

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    Yeah my 3.65's with 26" tires turn about 3000 at 65. Runs fine but sounds like it's begging for mercy. /forums/images/graemlins/rotfl.gif
     
  14. tecton

    tecton 1/2 ton status

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    yeah like in my case
    id say that the glasspacks dont help...make it sound like its about to explode
     
  15. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I used to really like my glasspacks. I kinda miss 'em.
     
  16. reeser

    reeser 1/2 ton status

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    [ QUOTE ]
    I say you swap to 3/4 ton axles. They'll already have the gears you want (4.10) and you'll be able to pull your tires.

    Those mickeys are trash. They're not going to be quiet because they're bias. Even radial mud terrains are going to be a quieter tire.

    [/ QUOTE ]

    i couldn't agree more!!! you can find a set for as cheap as 300 bucks. they're a direct bolt in and you'll never have to worry about rear end breakage. DO IT DO IT DO IT.

    [ QUOTE ]
    3/4 ton axles weigh more

    i can barely go as fast as id like to now...

    i know the thing about not using OD...but, what is the D rpm with 31's

    [/ QUOTE ]

    funny the weight doesn't seem to effect either of my trucks. i have 2 blazers with 1 tons (read significantly more weight) and i can go as fast as i want to. i've done 95 with my 87 on 38's before.
     
  17. reeser

    reeser 1/2 ton status

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    also
    you have a freakin 1200 watt stereo who the heck cares about tire noise, just crank up the tunes man.

    like was said before those mickey's suck, you'd be better off with a RADIAL m/t tire like bfg, cooper, dunlop, goodyear etc... /forums/images/graemlins/thumb.gif
     
  18. tecton

    tecton 1/2 ton status

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    i see about 1 day a month in the mud anymore, if that.

    So if i got another MT, it would have to wear incredibly long to warrent itself over an AT
     

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