Tire Growth

Discussion in 'The Comp Buzz' started by LEE HEWELL, May 17, 2018.

  1. LEE HEWELL

    LEE HEWELL New Member

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    I think this has been asked before, but I can't find anything more than wild guesses. Has anyone here studied tire growth and can tell me approximately how much I can expect from a 17X33.5 tire at 190 mph. I really don't want to risk tearing the body off my car to find out I don't have enough clearance. The car is a bantam altered and my options to get more clearance are limited.Thanks, Leland Hewell
     
  2. Charlie Yannetti

    Charlie Yannetti Well-Known Member

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    Good question, Lee.. I would point you in the direction or the manufacturer of the tire that you're running.. there are some variables involved, such as the rim width, sidewall construction, etc.. talk to their Tech, or Engineering Dept.. they should be close..
     
  3. Jim Primozic

    Jim Primozic New Member

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    Have you run the combination yet to have any race pak data if so I have a basic Excell spreadsheet to calculate the tire growth. You'll need to have access to the following info for it to work: drive shaft rpm at the 1/8 mile and 1/4 mile, MPH at the 1/8 and 1/4, rear end ratio and starting line tire roll out. If you have that info available I can send you the file to use it but if not it's pretty useless.
     
  4. LEE HEWELL

    LEE HEWELL New Member

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    Thanks Jim, I haven't run it yet. My concern is that the tires will grow too much and contact the body. I am looking for any info that might tell me if my tire clearance is too little before I run it and destroy my body. I guess I'm looking for an "educated guess". LOL
     
  5. Jim Primozic

    Jim Primozic New Member

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    Okay I run a goodyear 2053 occasionally and it grows to about 35.05 inches at 185 mph. So I'd say you'd be safe to consider 3 inches in diameter of overall growth.
     
  6. boostedf22c

    boostedf22c Active Member

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    I was told to make sure there was 4” of clearance between the tire and wheel tub. 200-205mph, 34” M/T tire.

    Seemed like a lot to me but that’s what was recommended.
     
  7. boostedf22c

    boostedf22c Active Member

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    Got ahold of my MT rep and he said this in relation to our tire growth, which is a stiff sidewall tire.

    “1.5-2 inch tops.. Your tire does not continue to grow like a high growth tire”

    For what it’s worth.
     
  8. 377 D/A

    377 D/A Member

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    what gear and rpm, is it at the stripe? when i was a dog that got kicked working on pro stock cars we made a program that would tell you rollout at the stripe and it was fairly accurate. i could verify it with the ride height laser. for instance, a tire we knew was 104" could be as much as 113" or as little as 110" at the stripe depending on speed,gear, and rpm. it was always interesting because you could have 6 or 7 sets of tires (which we did) and they all grew different. then you would always have a set or two that grew more or less always, regardless of outside factors. thats when it was fun, running splits in and out of the transmission trying to work with the set you were running on a given run. point is im not sure there is a great answer for you, and yeah i have burned up wheel wells on mtn motor cars before, adding a little wing angle to make it go down a horrible track and burned the 1/4 glass out of one. just tape it up and send it.
    ian
     
  9. LEE HEWELL

    LEE HEWELL New Member

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    Thanks for everyone's input. I really appreciate the help. The car has a 103 circumference and we currently have a 5.14 gear. I think with converter slippage, we will be around 9600-1000 rpms at the end of the track. If I understand your response correctly, The tire might grow as much as 3 in. in diameter. That makes me feel a little better about my clearance.Thanks again. Lee
     

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