I put skinny tires (225/60R16) on my polished pre-gen wheels for the winter since the belts were showing on my other tires. They're Cobra 5 spokes and I have 235/55R17 on them. The tread width and tire carcass is about 1-1/4" wider on the 235 than the 225. I guess the reason I'm bringing it up is for winter consideration. If someone is debating on width for tires that will see snow, consider that 10mm should equal less than 1/2" in width, but it's obvious in this case that it's not necessarily true. Perhaps the "235" is some sort of nominal dimension and not a physical measurement?
Cooper Mastercraft Avenger Touring LSR in both cases. Made in USA tires. 235s are 50,000 mile tires and the 225s are 80,000 mile tires, for reference.