My experience is that you might get good milage out of the factory tires but the ride like crap. Terrible in the rain, they never felt "Planted" for me, even when I bought it. This is just my experience.
2009 Road Glide. 16 in Vindikta Wild Cats. Aquatic AV, Stinger 700X4 to MMats PA 601, Audiopipe horns.
Ground Zero 7X10 in the lids w/ sspn.4 1000d, tuned with DD Audio DSI-2. S&S 106, lifters, push rods and AC. Drago 2. CycleRama 575. Progressive monotones -1in. 12in. HD adjustable rear shocks. Painted inner fairing. Tuned with TTS. Blacked out!