In a doubles combination, the driver completes a right turn. Which wheels are at greatest risk of running over the curb?

OFF-TRACKING in combination vehicles means the rear axles follow a shorter radius path than the steering axle — they cut inside the arc of the front wheels. In a DOUBLES COMBINATION, this effect is amplified: the off-tracking of the second trailer's rear axle is significantly greater than the off-tracking of a single 53-foot semitrailer. GEOMETRY EXPLANATION: Off-tracking increases with: greater overall length of the combination (doubles are 65-75 feet total); more articulation points (doubles have two — fifth wheel and converter dolly); sharper turns (tighter radius = greater off-tracking). PRACTICAL CONSEQUENCE: In a right turn from a two-lane road, the rear wheels of the trailing trailer may track over the curb, onto the sidewalk, or into the lane to the right of the intended path — even if the tractor appears to have swung wide enough. TECHNIQUE FOR DOUBLES: Must swing even wider before turning than with a single trailer; start the turn from further out; monitor the trailing trailer's rear path through convex mirrors; never allow pedestrians, cyclists, or vehicles to position themselves inside the turn path (the blind zone on the right); move slower through turns to allow constant mirror monitoring and adjustment.