If I have a 195 50 R15 what is the od of this ?
I am fitting 215 45 r 17 and looking to see if gearing is a problem .
this is on a type three automatic why I am asking , :party
well, 215/45/17 have an outside diameter (in inches) of 24.618, and a circumfrence of 77.340
a 195/50/15 has an OD of 22.677 and a Circ. of 71.242. Quite a big difference.
I have 215/40/17 which has OD of 23.772 and Circ. of 74.681
Hope that helps :thumb
I forgot to add that there's a 10% difference in the circ, so the speedo would also be out by 10%, but you knew that..
Thank you :beer
I see it will be better now with the subaru in the rear , as for the speedo I got a fix for that , in time I will show all 
Um where did you find the numbers please ?
A while back someone posted an excel program which did all the conversions for you. I downloaded it, and i just put in your dimensions. It calculated
the rest. I can email you the program if you like but I don't know how to put it up here.... send me your email address, it will be easier that
way:thumband faster
[Edited on 16-9-2004 by Oasis]
If you go here http://www.tirerack.com/tires/SearchTires.jsp
and choose a tyre size and select the specs of one you like the look of it gives the circumferences. If you pick a common one it brings up a big
chart with lots of sizes to compare.
Or http://www.mr2.com/FORMS/tire.html
for a comparison of tyre sizes, current size compared to new options with an allowable speedo error- quite a good calculator 
Or this one http://www.blackcircles.com/home?source=menu
I haven't used, but have seen the link around.
Cheers
Jeremy
Thanks guy very helpfull
its not very hard to do an a calculator
say for a 195/50 r15
2 * (195 *0.50) +15 * 25.4
this is the same for any tire it gives you the od in millimeters though so to go back to inches just devide by 25.4
to give an indication a stock 165r15 has an od of 650 mm or 26 inches
marcel