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Can I use 33" tires on my 1990 3.73 350 tbi?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by shum1, Oct 10, 2000.

  1. shum1

    shum1 1/2 ton status

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    Can I use 33\" tires on my 1990 3.73 350 tbi?

    I got a stock 1990 suburban that is going to be lifted, I want to put 33" tires on it. I have a 3.73 rear and no engine mods. Am I going to have enough power for this setup? I need to be towing a boat at altitude also. Basicaly I want to know how much power loss I'm gonna have with 33" vs my 31" tires. Thanks
     
  2. Blazer1970

    Blazer1970 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    I run 33s on my Suburban with 3.42s. It is not bad at all, but you don't use OD except at 70 mph plus. 3.73s would be fine (run in D not OD), but I would be a little concerned about towing. How much weight are you towing?

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  3. Derf00

    Derf00 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    shum,

    I recently installed a 4" lift and 33x12.5x15 MT on my Jimmy. It has 3.73 gears. I can honestly say that the differrence from 31's to 33's wasn't that great. I can tell a difference in mpg and a slight difference when accelerating, otherwise I am extremely happy with the 33's.
    Since there is a significant weight difference between the Sub and Blazer, I would suspect your preformance would be some what less but still quite acceptable. There are alot of people running 35's on 3.73's and think that their preformance is okay.
     
  4. 86blazerk5

    86blazerk5 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    33s, on 3.73s is perfect, the only qusetion is about your towing, the 350 should have the power, but like someone else question, iyt depends on the wieght and all.
    Ike

    Spreading The K5 Gosple!
     
  5. shum1

    shum1 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    Thanks for the replies, I tow about 3500lbs max. Also is there a way to recalibrate my spedo after the swap?
     
  6. Scoobydoo

    Scoobydoo 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    I have NEVER heard 3.73's are PERFECT for 33"s [​IMG] 4.11's would be MUCH better[​IMG].
    You should be OK with 3.73's but forget OD all together! and towing will definitely be effected, especially uphill (stay in the right lane)
    You say it is all stock? if you were to add a K&N aircleaner and a freeflowing exhaust like a "Cat back" or "True dual's" you should get "most" of the power back from the 31" to 33" change even with your 3.73's
    4.11's would be better and 4.56 would be IDEAL because of your weight, and towing, plus you would be able to use OD [​IMG]
     
  7. 86blazerk5

    86blazerk5 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    I didnt mean to say thet 3.73 would be perfect for 33s, What I meant was that it would be the factory equivalent of 3.42s with 31s. Which was a factory set up as well, so it would be just like running 3.42s, which should work fine even if you are going to be towing a 3500 pound object. however, if you are interested in swapping gears, 4.11s would be great.
    Ike

    Spreading The K5 Gosple!
     
  8. blazen91

    blazen91 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    I'm running 33's with stock gears on my 91 K5. 'OD' works ok but not great. I plan on changing my axles and will regear and run 35 or 36's.

    blazen91
     
  9. WakeBoard&4X4er

    WakeBoard&4X4er 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    If you want to get rid of your gears, i might want them. I have 33 and 3.42, and i am wanting to lower. If you want to sell them let me know.
     
  10. blazen91

    blazen91 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    Wakeboarder, If you're talking to me (blazen91) that's fine, you can HAVE them, however I don't know how soon I'll be changing over or what gears I even have. I should do a axle service soon and will let you know what I have.LATE!

    blazen91
     
  11. Sparky

    Sparky 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    I got 3.42's and 33's on my blazer. I dont use over drive mainly because it is not there. I tow a boat every now and then without any problems. The boat ramp is really steep, but it pulls it right out with no low range. I am not sure about pulling on the higway though. I just tow a limited distance.

    Sparky



    78 K-5
     
  12. WhiteWhomper

    WhiteWhomper 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    I ran 33" Widetrac radials on my stock '87 w/3.73 gears for quite a while and it did fine. I didn't notice much of a change in performance and I wheeled with those same tires without a lift and with a 4" lift over Moab and did really well. It did rub slightly without the lift but was fine with the 4" lift until I got sway bar disconnects and then it would rub again. Of course now I am subjecting my 10 bolts of fury to 36x12.5 Swamper TSL-SX's still with the same 3.73 gears.
     
  13. shum1

    shum1 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    W.Whomper, I see youre from Colorado, How did that stocker do going up Eisenhower tunnel? Did you ever tow anything? Could you use overdrive?
     
  14. WhiteWhomper

    WhiteWhomper 1/2 ton status

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    Re: Can I use 33\" tires on my 1990 3.73 350 tbi?

    I took it up through Eisenhower quite a few timesand I did fairly well. I didn't keep it in OD very much because it irritated me to shift up and down all the time. Still though not overly problematic.
     

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