Tire Size Calculator calculates tire diameter, circumference, revolutions per mile/km from the tire size designation on a tire.

This calculator also gives the option to compare tires. e.g., It compares the circumference and the outer diameter of one or more additional tires to the base tire and gives an information about upsizing/downsizing: does the new tire exceeds the recommended upper or lower limit for upsizing/downsizing. Also it shows the amount of speedo error due to changing the tire diameter/circumference.

Speedo error calculator calculates speedometer error as a result of the change in tyre size on a vehicle. It shows the actual speed your car is going after the tyre size change - installing the new tyres with a larger or smaller tyre diameter than the original equipment(OE) tyre. Also it might help with the speedometer calibration, to determine how much you need to calibrate your speedometer when you upgrade/downgrade your wheel/tyre size.

Wheel/Rim Size Calculator shows the acceptable wheel/rim width range for any given tyre size in accordance with the ETRTO standards and Databooks of the leading tyre manufacturers. It gives You the answer to the question "What rims fit my car?"

Wheel Offset/Backspace Calculator will help you to find the wheel offset and the backspace, the important measurements for positioning the wheel/tyre assembly inside the wheel well. It will help you to determine which wheels are adequate for your car. This calculator also gives the option to compare wheels, to compare the offset and the backspace of one or more additional wheels to the base wheel.

Tyre size for rim size/width calculator tells you what tyre sizes to go for, for the size of your rim. For eg., it gives an answer to the question: "I'm going for 6.5 x 15j rims. What's the best tyre size?"

It shows tyre width range for the selected rim(specifically, rim width), minimum and maximum tyre widths.

Select your rim size and click on the button "Find Tyre Size". The calculator will then tell you what tyre sizes(i.e., combinations of tyre width and aspect ratio) to go for, for the size of your rim(specifically, rim width).