tyre_calculator.js

const mmInOneInch = 25.4;
const mockRpm = 3000;

const tyreWidthInMm = 225;
const tyreHeightInPercentage = 45;
const tyreRimHeightInInch = 17;

const finalRatio = 3.38;

const someRevs = [2000, 2500, 3000, 4500, 5000, 5500];

const mockGearboxRatios = {
  1: 4.23,
  2: 2.52,
  3: 1.66,
  4: 1.22,
  5: 1
};

function getTyreHeightInMm(widthInMm, aspectRatio) {
  const percentageCalculation = aspectRatio / 100;
  const tyreWallHeight = widthInMm * percentageCalculation;
  const bothTyreWalls = tyreWallHeight * 2;
  console.log(`Total tyre sidewall height is: ${bothTyreWalls.toFixed(2)}mm`);
  return bothTyreWalls;
}

function getRimHeightInMm(rimHeightInInches) {
  const rimHeightInMm = rimHeightInInches * mmInOneInch;
  console.log(`Rim height is: ${rimHeightInMm.toFixed(2)}mm`);
  return rimHeightInMm;
}

function getTotalWheelHeight(tyreWidth, aspectRatio, rimHeight) {
  const rimHeightInMm = getRimHeightInMm(rimHeight);
  const totalTyreWallHeight = getTyreHeightInMm(tyreWidth, aspectRatio);
  return rimHeightInMm + totalTyreWallHeight;
}

function getWheelCircumference(wheelHeight) {
  const wheelRadius = wheelHeight / 2;
  return 2 * Math.PI * wheelRadius;
}

function outputReport() {
  const wheelHeight = getTotalWheelHeight(
    tyreWidthInMm,
    tyreHeightInPercentage,
    tyreRimHeightInInch
  );
  const circumference = getWheelCircumference(wheelHeight);
  Object.keys(mockGearboxRatios).forEach(key => {
    someRevs.forEach(revs => {
      let wheelRpm = getWheelRpm(revs, mockGearboxRatios[key], finalRatio);
      let wheelSpeed = speedInKmH(circumference, wheelRpm);
      console.log(`Speed @${revs}RPM in ${key} gear: ${wheelSpeed.toFixed(2)}`);
    });
  });
}

function reduceRpm(rpm, ratio) {
  return rpm / ratio;
}

function getWheelRpm(rpm, gearRatio, finalRatio) {
  return reduceRpm(reduceRpm(rpm, gearRatio), finalRatio);
}

function speedInKmH(circumference, wheelRpm) {
  return (wheelRpm * circumference * 60) / 1000000;
}

outputReport();