Believe it or not, it does depend on the year models of each. There were several supplier brands of components for many years. I think Paccar now uses either an in house brand or a preferred brand. Used to be several brands of components. My old 96' pete 377 with a 285" would turn circles around my 05' pete 379X with 270". But I think the brand new pete 389s will out turn them all at similar wheelbase.

 I watched a Western Star video about the newest models and the rep said they have teamed up with eaton as a supplier for everything. Engines, transmissions, front axles, rear axles and suspensions. They were talking it up about a best in class turning radius or the like.