confused about tire side profile

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by Nodus, Oct 14, 2017.

  1. Nodus

    Nodus New Member

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    I just ordered some new 17x7 front and 17x8 rears for my 79 Z28 and was wondering about tire sizes, i'm looking at some 245/45/17's for rear and somewhere in the range of 205-235 for the front but i'm confused about sidewall size, a lot of tires I'm seeing are 40 or 45, isnt that rating just for taller tires?
    say if i got some 225/40/17 and 245/45/17 would that mean my car camaro would just a little bit nose down?

    also looking for general recommendations on if i should have diff sizes or just have 45's all around?
     
  2. 74BIBELOT

    74BIBELOT Veteran Member

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    As I remember 245 the “ print” or road surface of the tire and /45-40 is the % of that print.
     
  3. Smokin'Joe

    Smokin'Joe Veteran Member Lifetime Gold Member

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    Tire sizes...., the 225 in your first question is 225 mm wide. The 40 in 225/40/17 means the sidewall is 40% of the 225 width of the tire. In the case of the 225/40/17 each sidewall is 90 mm tall ( there are 2 sidewalls, one above the rim and one below ). On the 245/45/17, the sidewall would be 45% of the 245, so the sidewall would be 110 mm tall. so yes, with those sizes, your rear tires would be taller than the front. - If you are going for similar aspect ratio front to rear, the fronts would need to have a higher number for the aspect ratio. As in you may want to go with a wider width 45 series in the rear, and a narrower width 50 series in the front, which may help result in having a more even looking front/rear. You may have to play with some numbers to find something suitable and although the widths and aspect ratio's are guidelines, each tire is a bit different, and may also be affected by the width of the rim you are mounting them on.

    If it helps, Summit has a lot of info on each of the tires they carry. - If you find one you are interested in, click on details and they will have data on heights/widths, and recommended rim sizes as well.


    Good Luck !


    --
     
    Last edited: Oct 14, 2017
  4. Nodus

    Nodus New Member

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    how would having all the same sized or diff sidewall profile effect the ride of the car? Good information thank you.
     
  5. GoldenOne7710

    GoldenOne7710 Equal Opportunity Offender Lifetime Gold Member

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    Different size tires won't affect ride quality....as long as both fronts match and both rears match.

    One thing to consider that these cars came with 14 and 15 inch wheels....which means there was a lot more sidewall/rubber for cushion and actually helped the ride quality. Bigger wheels mean shorter sidewalls to fit in the fenders...which means less of the sidewall cushion.

    You can improve loss of ride quality with some of these newer technology shocks and spring sets. Main thing is to make sure all of your suspension geometry is spot-on and your tires are properly balanced for a well riding car when using oversize wheels.
     
  6. Nodus

    Nodus New Member

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    My 79 has air suspension in the rear, it had some 295s on the back when i got it., i think i'll go with these 215/40/17 front and 245/45/17 rears, does that sound alright?
     

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