The mobile source particulate matter inventory includes exhaust emissions and non-exhaust emissions. Exhaust emissions include particulate matter attributable to engine related processes such as fuel combustion, burnt oil, and other particles that exit the tailpipe. Non-exhaust processes include brake wear, tire wear, suspension or resuspension of road dust, and other sources. Particulate matter from brakes and tires is defined as the airborne portion of the Ã¢â‚¬Å“wearÃ¢â‚¬ï¿½ that can be created by abrasion, corrosion, and turbulence. These wear processes can result in particles being suspended in the atmosphere. The size, chemical composition, and emission rate of particles arising from such sources contributes to atmospheric particle concentrations. However, these particles have different chemical composition and size than exhaust particulate matter. This report was drafted in 2008, based on a literature review conducted in 2006 and 2007. The algorithms and values discussed here were incorporated into MOVES2009 and carried over into MOVES2010 and later versions (MOVES2010a, MOVES2010b, MOVES2014) without change.