i was in a shop buying my helmet this weekend, and was talking to the guy about corner-weighting. he is active in autocross, and his shop doesn't offer corner-weight, so i can't imagine he's just trying to put down a competing shop.
he said i should ask what method they use to get the car onto the scales. if they just jack the car up, put the scales underneath and lower it, there is some pre-load left that will affect the readings. rolling the car onto the scales, he said, is the best way to do it. he remembered the last he had seen a couple years ago, they weren't using ramps.

i called the shop and they still use a lift to put the car on the scales. will the pre-load effect make the corner-weighitng process a waste of time and money? or is this still better than not doing it at all? i'm not aware of other local shops that have the scales at all, so not sure what other options i have.

thanks for your help,
phil