If I recall and understand the world of tires correctly, the tire pressure stamped on any given tire, is the max pressure it is rated for. The actual pressure you should use is based on several factors. The main factor (in my opinion, correct me if I am wrong), is the load the tire is expected to carry. The higher the load, the higher the pressure up to the max rating. NOW, since we do not carry a static load anywhere near the max rating of the tire, are we to consider dynamic loads (normal and hard landings)? And if so, how do we calculate the dynamic load? I think this may be where the confusion comes from. And when in doubt, do we use the max (pressure) that the tire is rated for? 70 lb would be very high compared to what we usually use, but the question remains, what are we supposed to use? If we were flying jets onto carriers, the tire pressure would be very closely monitored and kept at the higher limit would it not? Do your landings resemble a carrier landing? If the answer is "never", then use a lower pressure. Just how much lower, is the question? and does it hurt err on the side of higher pressure? Possible down side of overly pressured tires could be shimmy, ride quality (while taxiing), tire wear, lack of natural braking. But the most important of these could be shimmy.
No expert here. My opinions only.
Bevan