Can some provide the diameter of a tire of this size PLEASE???
45mm = 1.77 inches
1.77" x 2 = 3.54"
3.54" + 17" wheel diameter = 20.54"
That is the best I can do. Later I will go out an measure my 205/40’s and add the extra 10mm
HTH,
Mike
no no no . . . 45 isn’t constant measurement it’s a percentage
205/45R17
205 mm is the width
45 is the wall of the tire as a percentage of the width
45% of 205mm = 92.25mm
92.25mm * 2 = 184.5mm
184.5mm = 7.26" (184.5/25.4)
17" + 7.26" = 24.26"
or you can let my calculator do the math for you 
You are correct, I was wrong on that one. Sorry.
Mike
205/45/17 = 24.26 inches diameter
if you want to know whow its done here it is.
section width multiplied by the aspect ratio will give you a number. divide that number by 25.4 and that will equal the sidewall. multiply the sidewall number by two and then add the size of the rim and you end up with the overall diameter.
205 X 45 = 9225
9225 divided by 25.4 = 363
3.63 X 2 = 7.26
7.26 + 17 = 24.26
Originally posted by Speeddaddy
[B]205/45/17 = 24.26 inches diameter
if you want to know whow its done here it is.
section width multiplied by the aspect ratio will give you a number. divide that number by 25.4 and that will equal the sidewall. multiply the sidewall number by two and then add the size of the rim and you end up with the overall diameter.
205 X 45 = 9225
9225 divided by 25.4 = 363
3.63 X 2 = 7.26
7.26 + 17 = 24.26 [/B]
This sounds correct as the garage quoted me today 24.3".
Thanks everybody for your feedback
Originally posted by Speeddaddy
[B]205/45/17 = 24.26 inches diameter
if you want to know whow its done here it is.
section width multiplied by the aspect ratio will give you a number. divide that number by 25.4 and that will equal the sidewall. multiply the sidewall number by two and then add the size of the rim and you end up with the overall diameter.
205 X 45 = 9225
9225 divided by 25.4 = 363
3.63 X 2 = 7.26
7.26 + 17 = 24.26 [/B]
yeah that’s what I said! My math teachers used to always tell me to show my math . . . I guess I’ll never learn. Thanx for posting the how-to 
It’s amazing how easy it is, yet it’s one of those things that most people don’t know how to calculate . . … I guess it’s the whole mixing of metric and standard units of measurement thing?
Steve
http://www.miata.net/garage/tirecalc.html
Tire size calculator in addition to percentage calculator to compare between original and other sized ur considering… best part is it shows the difference in speedometer reading.
archivethis
tire size calculation