I assume you don't want to ditch the rims and go for ones that fit properly!

It all depends where the rubbing occurs. If the outer surface of the tyre rubs against the edge of the wheel arch, spacers are likely to make it worse, not better. You will need to get the edges of the arch 'rolled' or the fender 'pulled'. Both of these reshape the fender to create more clearance. This can be done by a competent body shop. Depending on the amount of the problem, this may not involve a repaint of the fneder.

If the rubbing occurs between the inside face of the tyre and either the inner panel or the suspension, then you may halp this with spacers. But remember this will make matters worse as above.

There's nothing wrong with using small spacers. Big ones will put unusual loads on the suspension.

You may be able to use a different tyre to solve your problems. Sometimes the same size tyre in a different brand will have enought of a difference in construction and shoulder profile to stop this kind of trouble.

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Cheers, Neil