Now, the final piece is revs / mile =

63360 (inches per mile) / (diameter *3.1415)

215/75x15 = 728.1950449 revs per mile

185r14  =  786.1958473 revs per mile

I hope my math is correct.

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Kim Brennan
Sent: Monday, April 18, 2005 2:05 PM
To: vanagon@GERRY.VANAGON.COM
Subject: [Norton AntiSpam] Re: whats the biggest 16" tire you can run on a
2wd vanagon??

There are differences in actual diameter between different brands of
tires and tread wear, however, the basic math is...

  tirewidth x ratio of sidewall x 2 / 25.4 (to convert millimeters to
inches) + diameter of wheel = diameter of tire.

[ 215 (mm) x .55 (ratio) x 2 (we're doing a diameter so it's in two
places) ] / 25.4 (mm's to the inch) + 16 (wheel diameter) = 25.31
inches
[ 205 (mm) x .70 (ratio) x 2 / 25.4 ] + 14 = 25.29

That's close enough not to worry (70% was the ratio on the tires not
75)...but let's do the match with 75% ratio tires...

[ 205 x.75 x 2 / 25.4 ] + 14 = 26.1

Standard tires (without a ratio value have the sidewall being 80% of
the tread width....)

[ 185 (mm) x .80 x 2 / 25.4 ] + 14 = 25.65

Syncro enthusiasts recommendation

[ 215 x .75 x 2 / 25.4 ] + 15 = 27.70

On Apr 18, 2005, at 1:27 PM, JordanVw@AOL.COM wrote:

> i talked to benT and he reccomended a 215-55-16 tire..  but someone
> else told
> me that this is "same as stock" rolling diameter of a 205 75 14???