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Roational Inertia ?

Discussion in 'Wheels / Suspension / Tires / Brakes' started by TRuggiero_, Feb 12, 2003.

  1. TRuggiero_

    TRuggiero_ Senior Member

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    Ok, so I read the articles on Rotational mass, sprung and unsprung weight. But one thing I didn't get, why no Twin Turbo Supra's rolling on 15's? The way I understand, the smaller the wheel, the less rotating mass, the faster it goes. Like the ice skater thing. Yet Supra on 18's is a must. Help me out here.
     
  2. SixtySecondAssassin

    SixtySecondAssassin Senior Member

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    brake size and ride height have an impact. it also weighs over 3000 lbs so it needs wheel that can support its fat ass.
     
  3. D See 2

    D See 2 Senior Member

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    werd - lol
     
  4. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    Hey, my fat bitch weighs a touch over 3000 lbs stock, and she rides on 15's stock. :D
     
  5. TRuggiero_

    TRuggiero_ Senior Member

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    Ahhh, so you have to find a complete equilibrium between how fat your bitch is and all that unsprung weight.
     
  6. SixtySecondAssassin

    SixtySecondAssassin Senior Member

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    damn. 3rd gen rx7's only weigh 2800. i didnt know accords weighed that much.

    a supra also needs a wide contact patch to put the power down. not too many companys make a 15x9 or 10
     
  7. dohcvtec_accord

    dohcvtec_accord WRX Sellout

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    The Accord EX sedans weigh that. I know that the DX sedans weigh 2800 flat.
     
  8. E_SolSi

    E_SolSi Member of the 20 nut club Moderator VIP

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    thats a big part of it... the contact patch also comes into effect
    the OD of the tire also contributes to the gear ratio... too small with a close ratio tranny and you will top out at a very low speed

    also Supras have this kick ass thing called Torque... apparently Honda never heard of it :(
     
  9. mwasnp

    mwasnp Senior Member

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    Its a brake thing partly. When a car is that fast from the factory they want fast braking ability, and you couldnt fit brake rotors large enough inside of a 15" wheel.
     
  10. chet

    chet Senior Member

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    everything is a compromise. bigger brakes will help to stop a vehicle with bigger wheels that make for a larger rolling diameter and more rotational mass. the car company's making these cars really know what they're doing. the size of the wheel on their cars are carefully calculated by engineers considering manufactoring costs vs performance vs economy.

    supra's don't run on 15's because they need bigger wheels to help put the additional power they're putting down. some grand prix cars run on 18's and 19's, simply because the brakes they need to stop the car and tires they need to hold the car have to be 8,9 and even 10 inches wide.

    you have to look at the entire setup, and remember that our little honda's weigh under 3k lbs and 15 x 7's are more than good enough for almost all civics.
     
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