function preloadImages() {
    pic101 = new Image();
    pic101.src = "/images/top-tab-alloys-on.gif";

    pic102 = new Image();
    pic102.src = "/images/top-tab-brake-discs-on.gif";

    pic103 = new Image();
    pic103.src = "/images/top-tab-brake-pads-on.gif";

    pic104 = new Image();
    pic104.src = "/images/top-tab-exhausts-on.gif";
}