South Dakota pushes speed limit to 80 mph

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80 mph in SD

Following passage of bills in the South Dakota state legislature earlier this year that boosted the state’s maximum speed limit, as shown in the tweet above, the S.D. DOT was hard at work prepping for the change. The change took effect on April Fool’s Day on I-90 and I-29 in portions of the state.

Find a recent USA Today report on trends in top speed limits, including this map graphic, via this link.Find a recent USA Today report on trends in top speed limits, including this map graphic, via this link.

South Dakota joins four other states with speed limits of 80 or higher: Utah, Wyoming and Idaho at 80 (though Idaho limits trucks to less with a split limit) and Texas in one spot up to 85. With speed limits creeping up, the Associated Press published this story the morning of March 31, which questioned the wisdom of such high speed limits for large trucks.

Before you take advantage of any top truck speed limit above 75 mph, consider that most commercial truck tires are rated for a maximum speed of 75 mph. Long periods running above the max speed may accelerate wear with built-up heat — which could ultimately result in tire failure. Most auto tires, meanwhile, are max-speed-rated much higher.

How much of a factor do you consider speed to be in tire wear? If you’re using a mobile device, tap the image to call and weigh in with a voice message we may use in a future “mailbag” podcast. If you’re on a desktop, call 530-408-6423. Be sure to include your name and base location in the message.How much of a factor do you consider speed to be in tire wear? If you’re using a mobile device, tap the image to call and weigh in with a voice message we may use in a future “mailbag” podcast. If you’re on a desktop, call 530-408-6423. Be sure to include your name and base location in the message.

Bridgestone, for instance, issued a statement this week in response to the AP report, reiterating that most of its long-haul tires carry a speed rating of 75 mph, though some have a speed rating slightly higher — 82 mph.

Michelin spokesperson Tony Fouladpour likewise says most of his company’s on-highway heavy-duty tires are rated at 75 mph, with some being rated for up to 81 mph. However, there are more factors at play than just manufacturer ratings and speed, he says. “Michelin provides commercial customers and fleets very specific and detailed information on the speed rating as it relates to tire pressure, proper wheels and load capacity — all of which are important factors when it comes to tire safety at any speed,” Fouladpour says.

In a quick scan of Goodyear’s online spec options, most of the company’s on-highway truck tires show speed ratings of 75 mph.

Note: More tire manufacturers were consulted for this article. Their input will be added when it becomes available. 

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