The laws have been on the books for some time, but the DOT sent out a ‘clarification’ in a June 2016 bulletin.
TIRE STRETCHING The act of installing a smaller tire on a larger wheel commonly known as tire stretching, may be unsafe in regards to safe operation of the vehicle. When inspecting a vehicle on which tire stretching is evident, inspectors should be vigilant to ensure the ‘reject if’ criteria listed in 175.80 is followed. Possible ‘reject if’ criteria that could be applied are:
• 175.80(b) Internal Inspection;(v) the front wheels can’t be turned to the full right or left position without binding or interference, (vii) the number of turns of the steering wheel from a straight ahead tire position to the position to the top right is not equal to the number of turns to the top left stop within a tolerance of ¼ turn.
• 175.80(e) Beneath the Vehicle Inspection; (ix) A tire’s tread extends beyond the outer edge of the wheel housing inclusive of fender flares; (xxii) A tire is smaller than the manufacturer’s recommended minimum size or below the manufacturer’s recommended load rating, (2) (iv) The steering stops allow the tire to rub on the frame or chassis parts; (v) The front wheels are incapable of being turned to the right and left steering stops without binding or interference.
Note: To determine if a tire is “smaller than the manufacturer’s recommended minimum size”, you will need to determine if the overall diameter of the tire is smaller than the recommended minimum size. To accomplish this, the inspector can utilize resources such as the tire manufacturer or tire retailer websites, web-based tire diameter calculators, tire diameter smart phone applications, or printed tire specification charts which are available from parts stores and tool suppliers.
• 175.80(f) Road Test; There is a malfunction of the braking or steering mechanism, particular shimmy, wander, pull or other questionable behavior that affects safe operation of the vehicle.