You need a transform between whatever TF frame your laser is publishing data and the "base_link" or equivalent frame that is the center of your robot. There is a link in section 1.2 of the tutorial you linked: http://wiki.ros.org/navigation/Tutori... - which walks through how to make sure you have TF working.
Creating a URDF is one possible way of having the TF data - or you could use the code shown in the link above -- or possibly easiest is to use the static_transform_publisher node found in the tf2_ros package.
Yes, you will need that or create something that at minimum publishes your transforms