Derrick,
I purchased from Wilkinson the 18 x 12.5 and 17 x 9.5 and I have to say you will have few issues:
You can go another 1" out in the rears if the offset is correct .. but you should tell the vendor what you want but the largest tire for a 18" wheel is a 335 18 30 Michelin Pilot Sport.
A 17 x 11 may fit the front but you will not be able to turn the wheels all the way inless the offset is correct and then the gr4 flairs will have to be pushed out further ?
Just my 2 cents on the research in tires and wheels.
Ron
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