They say max inflation pressure of 70 psi, but I doubt that's a good starting point.
++++++++++++++++++++++++++++ Something more scientific will hopefully emerge - in the interim, for what it is worth. Baron nose gear (500x5) carries about double (900lbs on one wheel) and calls for 50 psi Cherokee 6 nose gear (600x6) carries about the right weight as one KR wheel (approx 500lb) and calls for 28 /30 psi. I had a word with our A&P - I estimated a typical gross for 56ML of 1100lbs. Kenny suggests around 32 /35 psi for a tricycle and 38 /42 for a tail dragger - I gather that draggers offer more potential for high side-loads. He does not think the speed limitations will be reached on a KR - so anything from 5 ply up. Steve J