When is a farm tractor not a farm tractor? When it's a commercial motor vehicle.

That's how thousands of tractors, combines, and other agricultural vehicles could be classified if the Federal Motor Carrier Safety Administration (FMCSA) has its way. In late May, FMCSA issued a notice requesting public comment on how the agency regulates farm vehicles and their drivers, and whether states should change they way they apply those regulations.

FMCSA and groups such as the Commercial Vehicle Safety Alliance (CVSA) want to make farm vehicles subject to many of the same rules imposed on long-haul truck drivers. The proposed revision to 49 CFR Parts 383 and 390 (Docket no. FMCSA 2011-0146) would require drivers of farm machinery and other vehicles to abide by such regulations as the hours-of-service rule and commercial drivers license requirements. The agency also wants to ensure that the states consistently apply federal regulations to agricultural vehicles and that they adopt a uniform definition of who and what types of equipment are subject to those rules.

Will we soon see John Deeres and International Harvesters lined up at truck stops? Probably not. But over-the-road drivers who are renewing their CDLs may see a lot of guys in overalls waiting in line with them.