I used to have 305/50-15 tires on the back of my Pantera with 8" wide Campys, but the sidewalls looked pretty bulgy (is that a word?). The manufacturer's spec allowed for installation on an 8" wide wheel, but it didn't look nearly as good as the 295/50-15. And, I don't think anyone is making the 305/50-15 any more.
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