about 20 years ago tires were measured some what different.. The first three number are the width in millimeters, next two number are the aspect ratio, meaning the sidewall is a percentage of the width(i.e. 205/50---the 50 is saying that the side wall is 50% tall as it is wide or 102.5 mm tall), the next two number are the hole, meaning the rim size. You can trust me on this, I sell tires all day long. If you still don't believe me, call a tire dealer there in your town.well my fianc'e said the first three numbers are the diameter. 65 is the width, he also said that i could fit a 55 on a 15. he knows alot about cars he has a '72 plymouth duster its not a camaro but he said it should work.