Hello Damian,
Yes you are right - and when I had the original Swift supplied ordinairy radials I always ran these at 36 psi - as per the book. However, despite usual care and protection from the sun, these began to crack at just three and a half years. I then changed to Bridgestones which are re enforced. I am aware that some types of tyre used on vans, for instance commecials, require a higher pressure.... hence my question.