Hi, 4 wheel would be the only way I would go, recently at a main dealer, I was asked to look at a renault Espace which had a history of tyre scrub/squeal the tracking read right with their two wheel kit, but in order for the steering wheel to be centred the techs had adjusted the track rods unequelly, the steering wheel could only go on one way, and they were left with the choice of adjustement at the rack coupling end, I managed to borrow a four wheel tracking kit, which set all four wheels to the steering wheel, problem solved, other than the debate in the workshop over what was the right, and what was the wrong way to do the job.