OverRun, Thank you very much for taking the time to try and explain all of this for me.
The airfield I was using as an example was
ROCKFORD (RFD) not because I have any intention of going there, but just because it includes the code TRT.
I guess if an airfield doesn't list TD and only lists DT and DDT I'm stuck having to use the DT figure, or would it be reasonable/possible to interpolate between the two.
The ACN/PCN system is beginning to look so simple now!
Thanks for the point about the figures sometimes being in lbs rather than Kgs. The Aerodrome Directory I have access to (Aerad) states all its figures in Kgs, where as its becoming apparent that some of there figures are in Kgs but about 75% of the airfields listed (in the USA) are in fact in lbs! Doh!
A couple of other questions for you
1) I sometimes still see Isolated Single Wheel figures quoted.
e.g Rome (LIRF) ISWL45000.
Do I just multiply this by the number of main wheels?
2) The maximum certified tyre pressure for the B777-200 is 215 psi. So under the ACN/PCN system W and X codes are fine, but a few airfields have Y (Low, Max 145psi) listed even though the PCN number seems quite acceptable.
e.g.
Tel Aviv (LLBG) PCN 84/F/B/Y/U
Would I be likely to cause damage to the runway here, or is it just like JW411's dinners on Greek Islands?
Rgds SB777.