I began this chopper build by starting with the rear tire (picked up for free from the “Free” section of Craigslist.com. As you will see I then built the bike’s frame around the tire. This chopper uses a 15″ automobile tire as its rear tire. A 15″ automobile rim is the same size as a 20″ bicycle rim — something that will prove useful when building (i.e. lacing) the chopper’s rear wheel.