AP Racing have identified the actual size of the wheel necessary for a particular kit, and where possible have listed an example of an individual manufacturers specification, often other manufacturers wheels can be used, but inner wheel profile must be checked before fitment. It is usually the inner spoke area that causes the problem with fouling the outer face of the caliper.
The following links to a number of wheel manufacturers may be useful.
Compomotive | Revolution | Rimstock | TSW
AP Racing does not recommend the use of a wheel spacer or removal of material from the caliper or wheel as a cure. We now have some of the most common Caliper Profile Drawings available to download, these can be accessed from the relevant brake kit via the Application Guide .If the relevant profile is not available online, please Contact Us as in many cases a full size profile drawing of the brake kit is available by post.