It is the air pressure that defines how a tire "feels" and responds. Stiffer sidewalls make little difference. How much a tire deflects under load is determined by the pressure and volume of the air within. Stiffer sidewalls at lower pressures will actually increase tire heating and if operated that way can actually increase wear and potential failures. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of JRodgers
Sent: Wednesday, April 24, 2013 12:47 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: I hate to get a tire discussion

Gotta up the air pressure near the max for best performance - otherwise your van will be squirrely and  all over the road. Don't ask how I know!!

John

On 4/23/2013 7:53 PM, Max Wellhouse wrote:
> I've been very pleased with my Altimax's on my 96 Legacy Brighton 
> Wagon.  Guess I didn't realize that they had the "innard" to tacke the 
> Vanagon's weight.
>
> Good luck with the shopping regardless....
>
> DM&FS
>