Lots of brands of tires on the Tire Rack have 225/55/R16 available but not 225/50/R16. How much of an issue is it to have a sidewall only that much larger on a stock rear end? The suspension may be a little worn, but it is stock and not lowered.

 

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Plenty of options in 225/50-16. More Summer tire options than in 225/55-16 and a ton of all-seasons and winters available as well.