I bought a digital LCD tester with metric/inch conversion to check tire tread for a motorcycle trunk along with this basic tool and the Estimation accuracy isn't great, but it's close enough. I like both metric and standard markings and that was a very big reason I went with these over many others. Just know it's not entirely correct. Save some money and confusion before switching wheels haphazardly. This tool helps you understand where wheel alignment is based on tire wear patterns.