What do you mean by light dirt conditions.
If it is hard packed any tire will do.
If it is soft dirt then hard round tires will start to squirm under you.
The best thing is to air down to get a "flatter, wider" tire. This will help you float on top of the soft stuff.
A wider tire is better,....
About 45,000 miles ago I switched over to a car tire since I commute every day on my bike...
What I discovered was that the best air pressure was 28 lbs. It gives a nice soft ride...
One trip out through the Carrizo Plain National Monument was on a dirt road that had several shallow sandy patches.
My fellow riders on their big HDs with MC tires were squirming in front of me. While I floated over the sand on my ST1300a..
Gravel roads were no problem. YMMV....
Mud is a different story. Skinny knobby tires are better in mud. The tires need to dig in and cut the road to keep from sliding.
wide tires on mud will slide all over the place. I live in So. Cal...
The tire I am currenly using:
https://www.st-owners.com/forums/showthread.php?146717-Another-option-for-the-ST-BF-Goodrich-G-Force-Comp-2