When I modified and updated my wheels, suspension, sway bar, spacers etc.  
I found T3Technique very helpful!  They really seem to understand the Vanagon suspension.
http://www.t3technique.com/vanagon-suspension/

You may wish to reach out to them for advise for your particular application.  
As you know, the earlier Vanagons ride higher, which could impact handling as well.

For your reading pleasure.
https://rimsandtiresmag.com/7-things-you-should-know-about-wide-vs-narrow-tire/

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Sudhir Desai
Sent: Thursday, April 8, 2021 9:48 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Tires

I'm actually thinking about doing this to provide more rubber in the rear
of my 2wd vanagon.
17" wheels up front and 15" wheels in the back to provide more sidewall to
flex.

On Thu, Apr 8, 2021 at 8:59 AM Jack R <jack007@comcast.net> wrote:

> You could, but I wouldn't recommend it!
>
> Vehicles always perform best with like tires and sizes.  Mixed sets,
> driving straight no major issues, but handling on turns will feel odd at
> best, and worse at greater speeds.  The problem really surfaces in tough
> conditions, like weather, speed or emergency maneuvers.
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of John Rodgers
> Sent: Thursday, April 8, 2021 8:44 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Tires
>
> Can I run stock (14 in) tires up front and 16 in tires on the rear in a two
> wheel drive vanagon with autotranny?
>
> Thanks.
>