A plurality of ramp planks of a predetermined thickness are stackable on a frame, to determine the height of the ramp. Each successive plank, in the upper direction, is shorter than the one below it. The number of planks utilized determines the height of elevation of the wheel. The degree that a vehicle is off level is measured by an inclinometer carried by the vehicle. The reading on the inclinometer tells the user the number of ramp planks he should use so that when a low side wheel of the vehicle is driven up onto the ramp, the vehicle will be substantially level. Indicia is provided on the ramp planks corresponding to indicia on the inclinometer.