I was thinkin about upgrading my wheel size when i buy some spoke rims but i was wondering... when you change the size of your wheels what more do you have to *** i know you have to get new tires that fit and all but what else, i heard you have to some how change the RPM or something like that because if you dont ur mph meter will be wrong.  What are the other things you have to do other than new tires?  Small and big