The width of the tie should be in proportion to your body. Given my height (6"1") and waist(44"), I think 4" looks much better than say 3.5" or 3". Your suit lapels and shirt collars also need to be in proportion -- wide ties look quite silly when worn with suits with skinny lapels or shirts with small collars (I wear moderate spread collars that are 3 3/4" long). In addition, the tie should be long enough to reach the middle of your belt buckle (which in turn depends on how high you wear your trousers) while providing for the right sized tie knot (which also depends on the width of the lining materials) -- small knots look quite silly on heavy-set men. In my general experience, most RTW ties fail on at least one of these criteria. My bespoke ties are all 64" long, 4" wide at the base, around 2.75" wide approximately 20" from the base to allow for a nice knot with a dimple (the ties taper a lot so that they remain hidden under the collar) and lined with thick wool lining. I always use a four-in-hand knot.