Yes a heavy draft load will cause a small loaded radius decrease in the rear,
not as much as a heavy lift arm load.
It can also unload the front axle a small amount which could slightly increase the loaded radius.
/ B2150hst 4WD Tire Help - Lead/Lag Mechanical Ratio
Did not have time on Sunday to lift tractor and measure physical ratio. It was the last burn day of the season and needed to clear brush. Not sure when I can do the ratio test but it will happen so maybe other B2150 owners in the future can use the information.