This is one of our most commonly asked questions. Unfortunately, it has no easy answer. Picking a spacer that meets your needs is not as easy as it sounds. If it were easy, we'd all be using the same size. There are a few different reasons why people need spacers so every situation ends up being different. But every situation can be resolved by finding out how much available space you have to work with. That means measuring the tire-fender clearance. This empty space will likely be your spacer size. You don't want to exceed the empty space because that will lead to the tire rubbing on the fender. And you don't want to get too thin of a spacer because that may not meet your needs.