Tyre PSI questions.

[mjr]

ABout 60 - 65 should be more than sufficient for a 700 x 38c.

I'm not sure about that for @callummac. I run 65 rear and 45 front on 37s, but me, my bag and my bike weigh about 85kg combined. The Dutchie runs 80-85 rear on a 40mm at the moment, due to a dud Specialized tyre that has a high minimum pressure and feels rotten if softer.

 

[The_Weekend_Report_Guy]

As a heavy rider myself... I always run the max or near the max... Of whatever is recommended... If I don't do this I have pinch flats very often... They are very annoying so I learn my lesson... The only problem is that you might wear your tires off quicker then others... In my opinion totally worth it not to stop once a week or more because of pinch flats or snake bites as they are also known..
All the best..
P.