>1.  Is the high ply tires needed for vans because:
>
>a.) The weight of the van
>b.) Because the handling is so odd and the added ply is required for 
stifness
>and intern      better handling.
>c.) None of the above.

The answer is (b) and (c). And (d), if (d) is:

d) Most VW vans have huge cargo-carrying capacity-- see the "Gross Weight"
specification in the oweners manual. If you fill it up with firewood or
whatever until it reaches this max weight, you will overstress ordinary car
tires-- that is, load them to a higher weight than that specified on the
tire sidewall.