The perfect tool to calculate the difference in size between your current tire and your replacement tire (tyre). It will show measurements for the diameter, section width, sidewall height, revolutions per mile or kilometer and also speedometer reading. The PRO upgrade unlocks plus sizing. With plus sizing you simply enter your original tire size and your new rim width to see suggested sizes close to the original diameter. You can also convert a tire size to another format by entering the same rim width as the original (i. e. U. S. sizing to metric) This app offers several unique features: Compare multiple tires at once. Fast tire size input. Supports many size formats. Plus sizing. Tire size converter.