This ride uses all of the Lochside Trail, and all of the Galloping Goose Trail.  In between are mostly quieter roads around the Victoria region.  While this route has limited climbing (1350m), there are 85km of gravel riding.  While all can be ridden on 25mm tires (I once saw someone ride the Goose gravel on 19mm slicks, including the 2 steep gullies near Sooke), larger tires will be more comfortable.