The CHP was trying this evening to locate the truck, a black Ford F-250 towing a white boat, which did not stop after the crash, CHP Officer John Short said.
The crash occurred at about 4:40 p.m. on eastbound state Highway 4 near Lone Tree Way after the F-250 was reportedly tailgating a white Honda Civic, Short said.
He said the truck then made an unsafe lane change, which forced the Honda Civic into the motorcycle.
The motorcycle driver died at the scene.
Bay City News contributed to this story.