Rolling Radius Formula

abhaythomas27 · 28th January 2010, 14:58

Hey people. I'm kinda new in team-bhp, and my first question is really technical.. i've been searching the net a lot and cant find the formula to calculate the rolling radius of a tire. I know there are online calculators, but i want to know the formula too....

help!!!

Trust_In_Thrust · 28th January 2010, 23:44

i guess you mean the rolling circumference which is 2x3.14xRadius.
Radius of tyre = sidewall height + rim radius .
For eg : 145/80R12 mean 145mm width , Tyre Sidewall Height = 116 mm , Rim Radius = 6inch = 152.399 mm.
So total tyre radius = Sidewall + Rim Radius = 116 + 152.399 = 268.39 mm
Now Total Rolling circumference = 2x3.14x 268.39mm = 1685.48 mm = 66.35 inch

However please not that this may vary for even the same tyre depending on air pressure as it changes the sidewall height.

Regards

Nikhilb2008 · 28th January 2010, 23:51

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28th January 2010, 14:58	#1
abhaythomas27 Newbie Join Date: Jan 2010 Location: Chennai Posts: 4 Thanked: 0 Times	Rolling Radius Formula Hey people. I'm kinda new in team-bhp, and my first question is really technical.. i've been searching the net a lot and cant find the formula to calculate the rolling radius of a tire. I know there are online calculators, but i want to know the formula too....help!!!
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28th January 2010, 23:44	#2
Trust_In_Thrust BHPian Join Date: Nov 2008 Location: New Delhi Posts: 768 Thanked: 350 Times	i guess you mean the rolling circumference which is 2x3.14xRadius. Radius of tyre = sidewall height + rim radius . For eg : 145/80R12 mean 145mm width , Tyre Sidewall Height = 116 mm , Rim Radius = 6inch = 152.399 mm. So total tyre radius = Sidewall + Rim Radius = 116 + 152.399 = 268.39 mm Now Total Rolling circumference = 2x3.14x 268.39mm = 1685.48 mm = 66.35 inch However please not that this may vary for even the same tyre depending on air pressure as it changes the sidewall height. Regards Last edited by Trust_In_Thrust : 28th January 2010 at 23:46.
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28th January 2010, 23:51	#3
Nikhilb2008 Distinguished - BHPian Join Date: Jul 2006 Location: Bangalore Posts: 5,195 Thanked: 10,177 Times	Car Bibles : The Wheel and Tyre Bible Page 3 of 4
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