Sell those tires and install a proper set pronto!  Not only will your
driving comfort and safety improve, but you will be able to sell the newish
passenger car tires in good conscience to a car owner before your heavy
Vanagon causes unseen structural damage to the tires you have.  All of the
non-LT tires that POs have subjected my Busses and my Syncro to showed medium
to advanced stages of structural damage (i.e. sidewall bubbles or substantial
belt shifting) and they handled like crap compared to when I installed proper
ones.  That's my two cent's worth (all I'll have left after purchasing my new
BFG AT KOs)
-chris