IT L GO said:SIPING is done by placing your tires (new or used) on a specially designed machine that rotates your tires while making small virtually invisible 90 degree cuts in your tread. Don't be alarmed! Although the process is actually cutting your tread, it doesn't harm your tire in any way, it improves on it. Only under very close inspection can the SIPES even be seen, and you're more likely to tell by your improved driving experience than by visual inspection. Show me a video. You may be wondering if SIPING can weaken your tread see this animated presentation designed to answer this question.