This is what I've always heard and understood.
The VC is pretty senstive to mismatched tires..
to the degree that Syncro owner's should rotate 5 evenly worn tires ..
starting with 5 new identical ones.
so they all match very closely if you need to put your spare on.

( real hardcore types by 6 new tires and rotate 6 on a regular basis, so
if they loose one to a rock or whatever..
they still have an identical-size spare. )

if you have a regular VC and no decoupler ..
you should move toward having 5 identical tires., and rotate them on a
regular basis.

On 11/28/2012 9:29 PM, Dick Wong wrote:
> So how much difference in tire size is considered a mismatch?  I have
> 27x8.50-14s all around and the spare is 205/70x14. According to my tire
> calculator that's a difference of 1.63" between the two.
> -Dick-
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Dennis Haynes
> Sent: Saturday, November 24, 2012 9:19 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: New owner questions-Syncro ownership costs.
>
> Clip>
>
> Fuel economy, you do loose about 10%. 16 to 18 mpg is about normal.
> Tires, you need to maintain a matched set. I use 5, rotating the three on
> the right side as the right front seems to wear the fastest. If I have to
> replace 1 or 2 I place the new ones  one front-rear to keep the axle speeds
> matched.
>
> Clip>
>
> Dennis
>