Well the book says that you should be able to lift the track 2 or 3 inches above the second wheel at the front. This is a bit subjective. Too tight of course is hard on the sprockets and too loose results in track slap or loss of track altogether. In the old days we ran the belts a bit slack but with the new belting available now and the new hard sprockets it is better to run the tracks pretty tight. The newer sprockets tend to hold the cleat as it leaves the sprocket and this is much less prevalent if your tracks are tight. Wear at the sprocket is much less of a problem with the new sprockets available.