Why are my 17 x 7.5 wheels actually 18.5 x 8.5???

Re: Why are my 17 x 7.5 wheels actually 18.5 x 8.5??? (CT-passat)

Im sure i am just measuring the wrong dimension- IE am i correct that the lip is 18.5 wide and the extra inch and a half is what holds the tire on? In other words when someone says 17" that is how large the tire bore is, not how wide the wheel is. Am I correct in that assumption??

Re: Why are my 17 x 7.5 wheels actually 18.5 x 8.5??? (CT-passat)

What do your tires say for size?

Re: Why are my 17 x 7.5 wheels actually 18.5 x 8.5??? (jusanotharabbitracr2)

well i just got the wheels so I havent bought tires yet. But im told I need 225/45- 17 tires. I know the wheels are 17x7.5 as that is imprinted on the wheel and that is the same as the guy who sold them to me. I assume my explaination above is correct as I think about it, but it struck me as strange when I first measured them.
Can I use a larger tire? Id like to go wider for looks and to fend off curb rash. Is their any drawback to going a size wider?