I purchased this tyre depth gauge and I have used it on my tyres some days ago, and it works perfectly! I used to send my car into the garage to have my tyre depths measured; and because they were busy, this process would take all day long. But, with this gauge, all I need to do is to turn my front my wheels and easily measure the depth of the tyres, a job that only minutes to do. Just push the gauge to its maximum extent and then place the gauge onto the tyre in question and push down on to the tyre to get the best results. That's it, its that easy!