ok - so I am officially confused by all of this wheel stuff. Can someone
answer the questions below for me?

To set up a 1990 Syncro Westy with 15" wheels:

What is the required wheel offset? Is this "ET"?

Would a number higher or lower than the required offset result in the need
for spacers?

What is the relationship between wheel offset and spacer thickness? That is,
how does a person size a spacer to adapt a wheel without the required
offset?

What is the required centerbore? in both inches and mm?

Do alloy passat wheels from any year fit the vanagon syncro? What are the
required modifications to the wheel in order to make it fit, if any?

Does one have to get a wheel with a specific load rating? what is that load
rating?

TIA,

Kevin