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Originally Posted by Dupontster  I had 285's on my 98 2500HD and had no problems....
I compared the two sizes and the sidewall of the 65 is 7.8" and the sidewall of the 85 is 8.4"....The radius of the 65 is 15.8" and the radius of the 85 is 16.4"....The diameter of the 65 is 31.6" and the diameter of the 85 is 32.8".. The circumference of the 65 is 99.4" and the circumference of the 85 is 103.1". The revs per mile on the 65 is 637 and the revs per mile on the 85 is 614.0...Speedometer reading will be off 3.7% slow. When you read 60MPH you will actually be going 62.2 MPH.... |
You have way too much time on your hands.