function TireCalculator(sectionWidth, aspectRatio, wheelDiameter) {
	this.sectionWidth = sectionWidth;
	this.aspectRatio = aspectRatio;
	this.wheelDiameter = wheelDiameter;
	
	this.sidewall = this.sectionWidth * (this.aspectRatio / 100);
	this.wheelDiameterMm = this.wheelDiameter * 25.4;
	this.overallDiameter = this.wheelDiameterMm + this.sidewall * 2;
	this.radius = this.overallDiameter / 2;
	this.circumferance = Math.PI * this.overallDiameter;
	this.revsPerMile = 1609344 / this.circumferance;
	
	var scaler;
	
	if (this.aspectRatio < 50)
		scaler = 0.85;
	else if (this.aspectRatio >= 50)
		scaler = 0.7;
		
	this.recommendedRimWidthMin = Math.round(this.sectionWidth * (1 / 25.4) * scaler * 2) / 2;
	this.recommendedRimWidthMax = this.recommendedRimWidthMin + 1.5;
}

function speedometerChange(oldTire, newTire, speedReading) {
	return (newTire.revsPerMile / oldTire.revsPerMile) * speedReading;
}