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post #1 of 8 Old 06-21-2011, 11:18 AM Thread Starter
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tire sizes

im getting new tires and was wondering if i could go from 255/75/17 to a 285/70/17. first of will those tires fit and also can someone explain what the first two numbers signify?
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post #2 of 8 Old 06-21-2011, 11:32 AM
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Plug the numbers into this and it will tell you everything you want to know:

http://www.discounttire.com/dtcs/infoTireMath.dos

As you can see the new tires are only very slightly bigger so obviously they will fit.

Last edited by Jollydodger; 06-21-2011 at 11:35 AM.
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post #3 of 8 Old 06-21-2011, 11:35 AM
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Quote:
Originally Posted by jimmyeye View Post
im getting new tires and was wondering if i could go from 255/75/17 to a 285/70/17. first of will those tires fit and also can someone explain what the first two numbers signify?
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post #4 of 8 Old 06-21-2011, 12:53 PM
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First number is the tire section width in Millimeters, second number is tire section height as percent of section width.
So a 285 is about 30mm (1.18") wider than a 255 tire ( 285mm-255 mm = 30mm ) and due to the added width may cause some rubbing at full steering lock or full suspension travel on stock wheels.

Overall diameter on the 285 is also slightly larger
255/75R17 --> 255 / 100 X 75 X 2 / 25.4 + 17 = 32.06" Diameter
285/70R17 --> 285 / 100 X 70 X 2 / 25.4 + 17 = 32.71" Diameter

Note numbers are only approximate and actual numbers vary in either direction from the indicated tire sizes depending on tire brand, tire type and wheel width the tire is installed on.
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post #5 of 8 Old 06-21-2011, 03:09 PM
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Quote:
Originally Posted by Panamon Creel View Post
First number is the tire section width in Millimeters, second number is tire section height as percent of section width.
So a 285 is about 30mm (1.18") wider than a 255 tire ( 285mm-255 mm = 30mm ) and due to the added width may cause some rubbing at full steering lock or full suspension travel on stock wheels.

Overall diameter on the 285 is also slightly larger
255/75R17 --> 255 / 100 X 75 X 2 / 25.4 + 17 = 32.06" Diameter
285/70R17 --> 285 / 100 X 70 X 2 / 25.4 + 17 = 32.71" Diameter

Note numbers are only approximate and actual numbers vary in either direction from the indicated tire sizes depending on tire brand, tire type and wheel width the tire is installed on.
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post #6 of 8 Old 06-21-2011, 06:03 PM
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Quote:
Originally Posted by Panamon Creel View Post
So a 285 is about 30mm (1.18") wider than a 255 tire ( 285mm-255 mm = 30mm ) and due to the added width may cause some rubbing at full steering lock or full suspension travel on stock wheels.
I don't think an extra half inch + is going to cause rubbing, I could be wrong.
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post #7 of 8 Old 06-21-2011, 06:07 PM
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Quote:
Originally Posted by Jollydodger View Post
I don't think an extra half inch + is going to cause rubbing, I could be wrong.
^^^^^^^^^^^^^

Very minor rubbing. I did this same swap prior to my small lift !!!

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post #8 of 8 Old 06-21-2011, 06:31 PM
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I have 285X70X17 GY MTR mounted on moab wheels. Minor rub at full turn, but this can eliminated with spacers. The only lift I have is springs off a JKU Rubicon, gives me 1.5" of lift.

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Last edited by Born2run; 06-21-2011 at 06:35 PM.
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