Even with my car's non-flat wheels, which required jacking the front end up and down multiple times to remove, measure and adjust the tires frequently, I was able to align successfully even the camber (about minus 1/2 degree - not verified by reputable shop) on the front wheels of my car, sticking the tool on the brake discs when the car is off the ground (wheels not), then measuring the ground again (wheels mounted - tool on a steel ruler over the center of the rim) and make corrections for other aspects of the suspension and alignment (toe-in in/out) and adjustment. Again, this took a few tries and some time, but still saved me from the uncertainties and costs associated with possible unscrupulous dealings. The tool seems great for the price and probably accurate enough for my needs (I'll keep an eye on tire wear) even if only used once.