The T40-C has a 288 inch wheel base and a 55 degree steering cut, so I looked up a formula posted elsewhere and found:
CALCULATE DP TURNING RADIUS FROM WHEELBASE - FCCC - SINGLE REAR AXLE
Just got off the phone with FREIGHTLINER CUSTOM CHASSIS CORPORATION
CUSTOMER SUPPORT CENTER 1-800-FTL-HELP (1-800-385-4357)
INDEPENDENT FRONT SUSPENSION - 60 degree wheel cut:
wheelbase in inches / 0.866 = turning radius in inches (eg. DSDP @ 242”WB / 0.866 = 279.445” : 279.445/12 = 23.28ft. turning radius
STRAIGHT AXLE FRONT SUSPENSION - 55 degree wheel cut
wheelbase in inches / 0.819 = turning radius in inches (242” / .819 = 295.482 :295.482/12 = 24.62ft. turning radius
So substituting the correct values for the Tour Master you get 288/.819 or about 352 inches or 29.3 feet.
I believe this is the track the wheels travel, so allow more for front overhang and the substantial rear 'tail swing' you will have...