Aluminum is lighter, tires come in different ply's and can be very heavy. If you were really chasing weight savings you would not start with the wheels. Why are you chasing a few pounds on wheels? Not going to give you any extra horsepower. You can go sit on the throne and pinch one out before you go riding and save the same amount of weight. lol Aluminum rims are nice looking but in order to get one strength wise compared to stock you would have to get atleast .190's and most likely a bead lock which becomes heavier. It's all in what you want but it's not where I would look to shed some weight.