Ok, more tech info direct from Michelin (800-847-3435).

For regular vanagons, the MX Reinforced will work.

For campers, the MX will not (despite what Sears assures me). You must use
the Agilis to avoid some nasty sounding kind of sidewall blowout over time.

Before buying tires, check the door plaque for the requirements of your van.
Look for the inflation rates, max. weight requirements, and what the Load
Range is. The Michelin MX Reinforced carries a max psi of 40, which is fine
for the passenger vanagons, but not high enough for the extra weight of the
campers. Michelin's pressure specs for campers (at least for my '84) is
39psi in the front, 48psi rear. The Agilis tire (which is also a 6-ply
reinforced tire) runs a max pressure of 54psi., has a maximum weight rating
of 1875lb, and is an LRC, or "Load Rating C" tire, which is what campers
need.

Our vans are quite unique in having such a narrow tire carry so much weight.
Thus the need for the reinforced tire. Because of the engine weight in the
rear, it has an even higher requirement for inflation than most vehicles.
The camper weight just adds more weight to the equation. The result: tire
costs around $100 per tire. Ouch. Still, anyone know of anything cheaper,
please contact me.

BTW: Both the MX and the Agilis are rated Mud and Snow. The Agilis 61 is the
one recommended for Vanagons.

Steve