From 1974 to 1995, the National Maximum Speed Law banned states from setting speed limits above a certain level. From 1974 to 1988, that meant the top speed limit was 55 miles per hour. From 1988 to 1995 it was 65 mph. After 1995, Congress once again allowed states to set their own speed limits. The change had significant implications for the trucking industry and for tire manufacturers which may still not be understood 20 years later.
The safety rating for commercial truck tires does not include the speeds that trucks are now allowed to travel in some jurisdictions. No truck tire is rated for the speeds of 75, 80 and 85 mph that are allowed in 14 states across the country. The speed limits were set without consulting the tire industry or changing the safety spec required for heavy truck tires.
The administrator of the National Highway Traffic Safety Administration recently discussed options for dealing with the discrepancy between the top speed limits and the top speed ratings of truck tires. He suggested that the NHTSA may renew efforts to require electronic speed limiters on semi trucks. These limiters would address the speed limit problem, if approved.
The speed limiter requirement has been under consideration for years. Many trucking companies have policies requiring the devices even in the absence of a regulation requiring them. The remaining truck owners have been reluctant to accept the regulation and have called for more analysis into the cost and impact of the devices. The NHTSA has indicated that it will press the issue going forward.
Source: The Big Story, “Safety chief wants to cap big rig speeds to fix tire problem,” by Meghan Barr and Tom Krisher, 9 April, 2015