tire size roll out formula
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* B A N N E D *
Joined: Feb 2008
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From: bro ham, al, USA
tire size roll out formula
I've seen lots of tire size questions, maybe this can help you 
ie: P205/45R16
take section width(205) multiply by aspect ratio(45) = 9,225
9,225 divide by 1270(same for all tires) = 7.26
7.26 plus wheel size (16)= 23.26
23.26" tall overall diameter.
ie: P205/45R16
take section width(205) multiply by aspect ratio(45) = 9,225
9,225 divide by 1270(same for all tires) = 7.26
7.26 plus wheel size (16)= 23.26
23.26" tall overall diameter.
You can get most of that information from the FAQ's. If not directly, then through the sites listed in the FAQ's. 1010tires has a tire size calculator that lists all that information, as well.
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Joined: Jan 2000
Posts: 23,478
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From: Chicago
Re: tire size roll out formula (PI$TOL)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PI$TOL »</TD></TR><TR><TD CLASS="quote">I've seen lots of tire size questions, maybe this can help you
ie: P205/45R16
take section width(205) multiply by aspect ratio(45) = 9,225
9,225 divide by 1270(same for all tires) = 7.26
7.26 plus wheel size (16)= 23.26
23.26" tall overall diameter.</TD></TR></TABLE>
Huh?
It's easy to calculate the diameter of a tire.
205/45-16
Sidewall height = aspect ratio times treadwidth = .45*205 mm = 92.25 mm = 92.25/25.4 inches = 3.63"
Tire diameter is wheel diameter plus two times sidewall height = 16 + 2*3.63" = 23.26"
The difference between this and your calculation is that you're using 1270, a number you made up and have to remember, rather than going through the steps and logic to calculate the actual sidewall height and to convert millimeters to inches. (1270 = 100 * 25.4 / 2)
ie: P205/45R16
take section width(205) multiply by aspect ratio(45) = 9,225
9,225 divide by 1270(same for all tires) = 7.26
7.26 plus wheel size (16)= 23.26
23.26" tall overall diameter.</TD></TR></TABLE>
Huh?
It's easy to calculate the diameter of a tire.
205/45-16
Sidewall height = aspect ratio times treadwidth = .45*205 mm = 92.25 mm = 92.25/25.4 inches = 3.63"
Tire diameter is wheel diameter plus two times sidewall height = 16 + 2*3.63" = 23.26"
The difference between this and your calculation is that you're using 1270, a number you made up and have to remember, rather than going through the steps and logic to calculate the actual sidewall height and to convert millimeters to inches. (1270 = 100 * 25.4 / 2)
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