Thanks, DDG.
I must have overlooked it earlier, but I did find degrees in our manual also. For full trim, 18 degrees is quoted as compared to 29 for full rudder travel (This is without any rudder ratio input).
So a ballpark figure would be 62%. Whether this ratio is held, I still don't know.
The original problem I had was estimating how much turn I could get on the nosewheel with just rudder trim application: I assume Rudder Trim moves the nosewheel as trim backdrives the rudder pedals and the rudder pedals operate nosewheel steering. This is a big assumption as I have not seen any warnings in the 737NG manual about using Rudder Trim on the ground (particularly important on those aircraft which don't have nosewheel lockout pins). I seem to recall there are warnings for other, larger, Boeing aircraft in their manuals.
Full nosewheel steering is 7degrees, so 62% of 7 degrees is about 4.3 degrees. This is not much in terms of tyre travel on an NG, but if you attach a long towbar to the nosewheel, you could cause some serious damage to personnel and equipment (IMHO).
The pilots/engineers I have asked about this seem oblivious to this potential risk. Have I overlooked something obvious here?
Thanks.
Regards.
NSEU