It seems to me that the excess reserve capacity deals with the dangerous blowouts and such .
If I pick up a nail the tire just loses pressure . Then it is up to me to notice that the tire is going flat .
That gets us back to the basic point which is checking air pressure before towing each day .
I too have found that by feeling the temp of each tire when I gas up that I can tell if one is hotter than the other due to lower air pressure .
When that happens , out comes the high dollar , digital tire guage from radio shack !