Free tyre and battery tools

Simple calculators that work on your phone. They give general guidance, so always check your vehicle maker's advice.

• Tyre Date Code Decoder: How Old Is Your Tyre?

  Type the four-digit date code from your tyre sidewall and see when it was made, how old it is and what to do.

• Tyre Size and Speedometer Error Calculator

  Compare your original tyre size with a new size and see the change in diameter and how wrong your speedometer will read.

• Tyre Pressure Converter: PSI, Bar and kPa

  Convert tyre pressure between psi, bar and kPa, with a reminder on how to check pressure correctly.

• Tyre Tread Depth Checker

  Enter your tread depth in millimetres and see whether your tyre is good, getting low or needs replacing.

• Car Battery Size Code Decoder

  Type a battery code such as 40B19L or 55B24R and see what each part means, plus a checklist for finding a battery that fits.