Tire speed rating calculator shows a tire speed rating, i.e., the maximum allowed tire speed(in kmph or mph), specified by its speed symbol.
The tire speed symbol of a passenger tire indicates the maximum permitted speed(in kmph or mph) the tire can sustain when properly inflated, under certain service conditions specified by the tire manufacturer.
Tire load rating/index calculator shows the maximum permitted load(in kg or lb) the tire can carry, specified by its load index.
The tire load index of a passenger tire is a numeric code that corresponds to the maximum weight(in kg or lb) that the tire can sustain when inflated at its maximum permitted air pressure(cold), under certain service conditions specified by the tire manufacturer.
Tire Size Calculator calculates overall tire diameter, circumference, revolutions per mile/km and sidewall height, from the tire size designation on a tire.
This calculator also gives the option to compare tires. e.g., It compares the tire circumference and the overall tire diameter of one or more additional tires with the base tire and gives an information about the tire upsizing/downsizing: does the new tire exceeds the recommended upper or lower limit for the tire upsizing/downsizing. Also it shows the amount of speedometer 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?"