I can attest to the need for having the correct tire on a Vanagon, especially
the heavier campers.

I have an '82 Adventurewagen with the correct, C-load-rated, reinforced sidewall
tires. The vehicle handles well, and it doesn't lean more than it should in
turns. Steering is precise, ride is good.

In stark contrast, I have an '87 Westfalia that I just acquired, and the
previous owner had installed some Sam's Club passenger car radials, General
Ameri 400's or something like that. This van, though not as top-heavy as my
Adventurewagen, leans a lot more in turns due to the sidewall flexing. It's
actually quite disconcerting when you take a turn too fast. I know I also need
new shocks, but the tires are largely to blame. The handling is somewhat vague,
and I don't get as much "feel" of the road as I do in my other van.

It's better to spend a little more on tires now. You won't regret it. I believe
Costsco sell their own brand of reinforced-sidewall tires that are appropriate
for the Vanagon, and they are less than $60 each. I plan to purchase a set
myself.

Hope this bit of anecdotal evidence helps...

...Dan