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Need advice tire size change

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Need advice tire size change

  #1  
Old 02-13-2019, 05:46 PM
Tuff Antypovich
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Default Need advice tire size change

Hey everyone I have a 2014 2500 Cummins with the rim size of 285 60r20 and was wondering what would happen if I put 275 60r20 size on the rims and if itís doable
 
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Old 02-13-2019, 06:43 PM
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Certainly doable. Your speedometer will be off, unless it's corrected. Most of the major tire stores can do that for you though.
 
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Old 02-13-2019, 09:56 PM
Pedro Dog
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You won't notice a difference. The 285s are 33.5 inches tall and the 275s are 33 inches. That's a 1.5% difference, so at 100 MPH the speedometer will be off by 1.5 MPH.
 
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Old 02-14-2019, 08:30 AM
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There are many tire size calculators available online to assist you in your search for information.......
 
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Old 02-14-2019, 12:21 PM
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here is how to figure the size.

285 60R20
285 mm is the width
60 is the % ratio of the side wall
20 is the rim size in inches
there are 25.4 mm per inch

so take 285 and divide it by 25.4 => 11.22 inches wide tire
the side wall then is 11.22 x .60 => 6.73 inches tall
you have 2 side walls, the top and the bottom, 6.73 x 2 => 13.46 inches of sidewall plus the 20 for the rim gives you the 33.46 inch tire

 

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