//You need an anonymous function to wrap around your function to avoid conflict
(function($){
    $.fn.extend({

        time        : null,
        eleWidth    : 0,
        windowWidth : 0,

        minWidth: function() {

            return this.each(function() {
                $wraper = $( this );
                $wraper.thisResize( false );
                $wraper.timer = setTimeout(
                    function(){
                        $wraper.thisResize( true );
                    },
                    100
                    );
                $( window ).resize( function() {
                    $wraper.thisResize( false );
                });
            });
        },

        thisResize: function( timeout ){
            $this = this;
            $this.windowWidth = $( window ).width();
            $this.eleWidth = 0;
            $this.children( 'ul' ).each( function(){
                $elementWraper = $( this );
                $this.eleWidth = $this.eleWidth + parseInt( $elementWraper.css( 'marginLeft' )) + parseInt( $elementWraper.css( 'marginRight' ));
                $elementWraper.children( 'li' ).each( function(){
                    $element = $( this );
                    $this.eleWidth = $this.eleWidth + $element.outerWidth( true );
                });
            });
            if( $this.windowWidth > 975 /*$this.eleWidth + 8*/ ){
                $this.css({
                    width: '100%'
                });
            } else {
                $this.css({
                    width: 975 /* $this.eleWidth + 8*/ + 'px'
                });
            }
            if( timeout ){
                $wraper.timer = setTimeout(
                    function(){
                        $wraper.thisResize( true );
                    },
                    100
                    );
            }
        }
    });
})(jQuery);