Interpretation ID: aiam1669
President
Stoughton Trailers
416 South Academy Street
Stoughton
WI 53589;
Dear Mr. Wahlin: This responds to your October 15, 1974, letter to the Bureau of Moto Carrier Safety asking if a trailer is subject to Standard No. 121, *Air brake systems*, if its buyer certifies, for tax purposes, that the vehicle in fact uses the highways only incidentally.; I have enclosed a discussion of our regulatory authority over moto vehicles, which does not include vehicles intended and sold solely for off-road use. However, we do regulate vehicles which use the highway on a necessary and recurring basis, whether or not this use is infrequent and incidental to the vehicle's working function.; We do not base this distinction on the same considerations as underl excise tax regulations and laws. The statutory definition of 'motor vehicle' and the regulations in the tax area differ from ours, as they are only directed to taxing regular highway users who should bear the burden of maintaining the roads. In contrast, our statute and regulations are directed to safe vehicle design, which is important for all vehicles designed to use the highways, whether or not their use is on a regular basis. We conclude that the revenue considerations involved in tax cases are not relevant to our safety regulation requirements.; Yours truly, Richard B. Dyson, Acting Chief Counsel