In a boat trailer for hauling a tunnel hull speed boat, wheels revolvably mounted on a cradle on which the boat rests are arranged to allow the periphery of the wheels to engage the overhead of the tunnel of the boat to permit the boat to roll easily from the trailer when released to do so, and to be easily mounted on the trailer from the water when the boat is afloat. The wheels are preferably mounted on stanchions, and arranged to be raised to the overhead engaging position from a position at which the wheels are not supporting the boat.