If a wheel is made for, lets say, a 215 tire, can a 225 fit on it? Thanks.

 

A wheel isn't "made for" any particular tire width. Each wheel has a width, usually measured in inches. Best way to determine whether a given tire will fit is to look up the specs on that particular size and model of tire on the tire manufacturer's website, where it will give the range of acceptable wheel widths.

 

that's one problem i have. I don't know the width. I do know that a 215 is flush with the wheel. would that make it 7" or 7.5"?

 

215 should work on a 7", definately on 7.5" i wouldnt do it on less then a 7".

 

You can fit anything from a 215 to a 235 on a 7 inch rim. 235 is pushing it though. I've heard of people putting 225 tires on a 5.5 inch rim...scary.