The National Highway Traffic Safety Administration (NHTSA) wants to change the test pressure for temporary spare tires from 52 psi to 60 psi, which would "marginally" increase the stringency of the test, according to agency officials.
The proposed ruling also would harmonize Federal Motor Vehicle Safety Standard (FMVSS) No. 109 with international and voluntary consensus standards. NHTSA reports that the Tire & Rim Association petitioned for the change in 2007.
For temporary spares, FMVSS No. 109 specifies test requirements for bead unseating resistance, strength, endurance and high speed performance. The standard also defines load ratings and tire labeling requirements.