function oldmeasures(){
		oldhalk = (document.tirecalc.olds.value * 2.54) + ((document.tirecalc.oldw.value * document.tirecalc.oldp.value) * 2);
		oldhalk = Math.round(oldhalk*10)/10;
		document.tirecalc.olddia.value = oldhalk;
		oldymp = (document.tirecalc.olddia.value * 3.14);
		oldymp = Math.round(oldymp*10)/10;
		document.tirecalc.oldperi.value = oldymp;
		return;
		}
	function newmeasures() {
		newhalk = (document.tirecalc.news.value * 2.54) + ((document.tirecalc.neww.value * document.tirecalc.newp.value) * 2);
		newhalk = Math.round(newhalk*10)/10;
		document.tirecalc.newdia.value = newhalk;
		newymp = (document.tirecalc.newdia.value * 3.14);
		newymp = Math.round(newymp*10)/10;
		document.tirecalc.newperi.value = newymp;
		return;
		}
	function calcspeed() {
		old_speed = 1000000 / (document.tirecalc.oldperi.value);
		difference = document.tirecalc.oldspeed.value * 1;
		new_speed =  1000000 / (document.tirecalc.newperi.value);
		speed_diff = ((100 * (old_speed / new_speed)) - 100) + difference;
		speed_diff = Math.round(speed_diff*1)/1;
		document.tirecalc.newspeed.value = speed_diff
		return;
		}