The easiest way to get this Achievement is to select Quick Race, then Sprint. Set it to the shortest length available, 3 laps, and the AI difficulty to Rookie, so you have no trouble in winning the race. Now it's just a simple matter of winning the race (an absolute doddle with the AI set to Rookie) and remembering to pull back on LS just before crossing the start/finish line on each lap to pull your ATV into a wheelie. Do this on every lap, and the Achievement will pop as soon as you win the race.