[{"data":1,"prerenderedAt":24},["ShallowReactive",2],{"content-tire-size-calculator-en":3},{"about":4,"steps":7,"faq":11},[5,6],"A tire size like 205\u002F55 R16 91V is full of measurements: 205 mm width, a sidewall of 55 % of the width, a 16-inch rim, load index 91 (615 kg per tire) and speed rating V (up to 240 km\u002Fh). The calculator derives the sidewall height, outer diameter, rolling circumference and revolutions per kilometer.","With a second size you see how much the diameter changes and what that means for the speedometer, e.g. when moving to larger rims. The tool also suggests sizes with almost the same diameter and reads the production date from the DOT code. Everything runs right in your browser.",[8,9,10],"Enter your current tire size, e.g. 205\u002F55 R16 91V. It is printed on the sidewall and listed in the vehicle papers.","Optionally enter the new size to compare diameter and speedometer reading, or pick one of the suggested alternatives.","For the tire age, type the last four digits of the DOT code from the sidewall.",[12,15,18,21],{"q":13,"a":14},"How much may the rolling circumference differ?","There is no fixed percentage for every vehicle. Binding are the sizes in the vehicle papers (CoC) or an approval from the car, tire or rim maker. The tool rates up to 2 % as small, 2–3 % as worth checking and more than 3 % as large – this is guidance only.",{"q":16,"a":17},"What happens to the speedometer with larger tires?","The speedometer is calibrated for the rolling circumference of the original tires. If the new tire is larger, each revolution covers more distance, so the speedometer shows less than you actually drive. The tool shows the real speed when the speedometer reads 100 km\u002Fh.",{"q":19,"a":20},"How do I read the age from the DOT code?","The last four digits of the DOT code on the sidewall give the production week and year: 2319 means week 23 of 2019. A three-digit code dates from before 2000.",{"q":22,"a":23},"How accurate are the calculated dimensions?","They are the theoretical nominal dimensions without load. Under the weight of the car the effective rolling circumference is slightly smaller, and every tire model differs a little. For comparing two sizes this hardly matters. What a trip costs in fuel is answered by the [[fuel-cost-calculator]].",1793808252667]