Crumb rubber is a material produced from recycled car tires.  The rubber from these tires is ground into particles, 6 mm or less and used for other markets.  One such market is for athletic fields.  Topdressing crumb rubber has shown to reduce surface hardness and increase turfgrass wear tolerance under simulated athletic traffic.  Plots containing ‘Thermal Blue’ Kentucky bluegrass (HTBG), and ‘Riviera,’ ‘Quickstand,’ and ‘Tifway’ bermudagrasses, were topdressed twice at 2.93 kg m^-2 each to achieve a 2 cm depth.  Traffic was applied to each plot using a Cady Traffic Simulator at low (2 passes week^-1) and high (6 passes week^-1) traffic levels to simulate athletic field wear.  Timing of traffic applications coincided with actual fall athletic seasons ranging from October to December 2005 in Knoxville, TN and Fayetteville, AR.  Prior to this study, comparisons between Kentucky bluegrass and bermudagrass varieties as well as comparisons between improved seeded varieties (Riviera) and vegetatively established 'Tifway' and 'Quickstand' bermudagrasses for use in transition zone athletic fields had not been made.  ‘HTBG’ proved to be acceptable for use in transition zone athletic fields.  ‘Riviera’ showed comparable wear tolerance to ‘Tifway’.  ‘Quickstand’ showed the lowest wear tolerance of the varieties tested.  Crumb rubber topdressing resulted in a significant increase in turfgrass wear tolerance, and a decrease in surface hardness, soil bulk density, and shear resistance.