Tire Conversion Chart.

Discussion in 'Exterior' started by powerhour, Jul 16, 2010.

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  1. powerhour

    powerhour Senior Member

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    i hope this helps!

    225/85R 14 = 29 X 9.00 X 14
    215/75R 15 = 28 X 8.50 X 15
    215/85R 15 = 29 X 8.50 X 15
    225/75R 15 = 28 X 9 X 15
    235/75R 15 = 29 X 9 X 15
    325/60R 15 = 31 X 12.50 X 15
    Q78-15 = 35.50 X 11.00 X 15
    215/70R 16 = 28 X 8.50 X 16
    225/70R 16 = 28.50 X 9 X 16
    225/75R 16 = 30 X 9 X 16
    235/70R 16 = 29 X 9.50 X 16
    235/85R 16 = 32 X 9.50 X 16
    245/70R 16 = 30 X 10 X 16
    245/75R 16 = 31 X 10 X 16
    255/70R 16 = 30 X 10.50 X 16
    255/85R 16 = 33 X 10.50 X 16
    265/70R 16 = 31 X 10.50 X 16
    265/75R 16 = 32 X 10.50 X 16
    265/80R 16 = 32.50 X 10.00 X 16
    275/70R 16 = 31.50 X 11 X 16
    285/75R 16 = 33 X 11.50 X 16
    295/75R 16 = 33.50 X 12 X 16
    305/70R 16 = 33 X 12.50 X 16
    305/85R 16 = 36 X 11.50 X 16
    315/75R 16 = 35 X 12.50 X 16
    325/70R 16 = 34 X 13 X 16
    325/80R 16 = 37 X 13 X 16
    365/65R 16 = 35 X 14.50 X 16
    Q78-16 = 35.50 X 11.00 X 16
    265/70R 17 = 32 X 11.50 X 17
    275/70R 17 = 32.50 X 11.00 X 17
    285/70R 17 = 33 X 11.50 X 17
    295/70R 17 = 33 X 12.0 X 17
    305/70R 17 = 34 X 12.00 X 17
    315/70R 17 = 34.50 X 12 X 17
    255/55R 18 = 29 X 10.50 X 18
    285/60R 18 = 32 X 11 X 18
    285/65R 18 = 33 X 11.50 X 18
    325/60R 18 = 33 X 13 X 18
    325/65R 18 = 35 X 13 X 18
    355/65R 18 = 37 X 14 X 18
    305/50R 20 = 32 X 12.50 X 20
    305/55R 20 = 33 X 12.50 X 20
    325/60R 20 = 35 X 13.00 X 20
    355/60R20 = 36.50 X 14.00 X 20
    325/50R22 = 35 X 13.00 X 22
     
  2. glass3222

    glass3222 Senior Member

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    Good info.

    Or if you want to convert it yourself:

    1. take the first number (the width in millimeters) and divide by 25.4, this give you the width in inches

    2. multiply be the second number (aspect ratio) divide by 100 (percentage), this gives you the sidewall height

    3. multiply by 2, the add the 3rd number (wheel diameter)

    Example: 275/60 R20 (factory 20" Ram tires)

    1. 275/25.4= 10.82677 inches

    2. 10.82677*60/100 or 10.82677/.6 = 6.496 inches

    3. 6.496*2 = 12.992 + 20 = 32.992 = 33" tire height.
     
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  3. Deviate

    Deviate Senior Member

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    That chart and formula will get you in the ballpark, but depending on the manufacturer the actual tire height will vary because of tread pattern or what have you. Case in point:

    265-70-17 AT tires:
    Formula Height: 31.61
    Nitto Terra Grappler actual height: 31.57
    BFG AT: 31.8
    Dick Cepek Radial F-C II: 31.7

    Not that a 10th of an inch makes that much real world difference, but just pointing that out.
     
  4. ramhunter9

    ramhunter9 Supporting Member

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    good info fellas .. stickie time
     
  5. ramhunter9

    ramhunter9 Supporting Member

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  6. StLucieHemi

    StLucieHemi Member

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    Here's a handy calculator I've been using for years, it has a nice feature of showing you size differences as well!!


    Tire size calculator
     
  7. Stangshcky12

    Stangshcky12 Super Moderator Staff Member

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    I used that calculated till I found this one, extremely handy!
    Tire Size Calculator - tire & wheel plus sizing
    It tells you what the original tire by vehicle and allows you to compare to different sizes and tells you the %differences
     
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  8. usmc1217

    usmc1217 Member

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    S0CAL likes this.
  9. Birddog

    Birddog Senior Member

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    Great post. That's a lot of typing!

    Sent from my Note 3 using Tapatalk Pro!
     
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  10. 2012Outdoorsman5.7

    2012Outdoorsman5.7 Junior Member

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    I keep trying to figure out for the tires im planning on buying but dosent seem right, Let me know what you guys get.

    285/65/20

    295/65/20


    Thanks.
     

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