If your tyre tread measures less than 4 mm your braking distance can extend by up to 60 why keep driving to the petrol station to measure your tyre pressure with this device you can measure your tyre pressure 0 8 bar 0 120 psi and tyre tread 0 16 mm at any time the results are shown on a lcd display comes with key ring and beltclip includes 3 v coin cell