NHTSA KICKS TIRES, TWEAKS PERFORMANCE STANDARD

The National Highway Traffic Safety Administration (NHTSA) has made a few changes to its tire standards in response to several industry petitions.  In June 2003, NHTSA established Federal Motor Vehicle Safety Standard (FMVSS) No. 139, which upgraded the tire performance requirements for most new tires on vehicles with a gross vehicle weight rating of 10,000 pounds or less.  The new standard largely replaces FMVSS Nos. 109 and 119, which have historically applied to passenger car and light truck tires.  Nevertheless, all bias ply tires will continue to be regulated under FMVSS No. 109, along with radial tires for passenger cars manufactured prior to 1975.  FMVSS No. 139 takes effect on September 1, 2007, although voluntary compliance is permitted before that date. Responding to the petitions, NHTSA has decided that radial tires with a tread depth of 18/32 inches or greater may continue to be regulated under FMVSS No. 119.  These tires are frequently used for off-road operations.  NHTSA determined that the thickness of the tread rubber makes it difficult to achieve the performance requirements of FMVSS No. 139 and reducing the thickness would diminish the tires�f off-road navigational capabilities.  NHTSA also accommodated the special characteristics of radial snow tires regulated under FMVSS No. 139 by reducing the endurance and low-pressure test speeds for those tires from 120 km/h to 110 km/h.