mine are fr500 wheels. you can run 17x9 all around on stock fenders (with coilovers), or 10/10.5 in back with pulled/flared fenders, and/or skinny tires.
they're cheap on ebay, or several mustang wheel sites (google mustang wheels or whatever).
btw, most mustang wheels come in the same sizes:
17x8 +30
17x9 +24
17x10.5 +27
18x9 +24
18x10 +22
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