Terry,
I kept the stock Chrome Rims and installed 275/55/R18 Toyo Proxes ST tires after just 70 miles on the original Michelins (235/65/R18). They fit perfectly with zero rubbing and zero modifications to make them fit. I don't think you can go any larger (wider) given the stock 44mm offset on the OEM wheels. The stock tires were 30.0" tall and my new Toyo's are 29.9" so there are no speedo issues either. There is a chance that 285/55/R18 may fit, but I haven't test fitted them (30.3" tall). /Brad
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