The pressure you use is dependent on your weight, the tyre size and the road surfaces you expect to experience. The maximum pressure recommended by the manufacturer is, IMHO, to be used on a perfectly smooth surface such as a track. Using too high a pressure not only causes a harsh ride, but can result in poorer grip due to tyre hop on rough bends. On the other hand, too low a pressure can result in a distinctly unsafe ride due to lack of grip and a tendency to p***tures.
As in many things, the ideal is somewhere between. You can only experiment to find your ideal. If it helps, I am 11 stone in weight and use 23mm tyres on my road bike. I use 90psi in the rear and 80psi in the front. I find this an excellent compromise between comfort and grip and p***ture resistance. (No p***ture in three years).