Just pulled out my dynamics book so I can use the proper terminology. That way if anyone that already posted is actually educated on the subject and not just pulling terms out the ass, it might make sense to more than just one person. So here my version of the story goes...
Mass moment of inertia (I)... "is a measure of the ability of the body to resist a change in its angular motion". In this case, the the angular motion is rotation of the wheel (hopefully no one's lost yet). There's equations for a ton of different shapes, but the closest to a universal rim would be a hollow cylinder, since most of the weight is at the edges of the rim. The equation is I = mR^2, where R is the radius to the inside of the cylinder. So you can see how the Mass will change this, but the radius has a large impact on the inertia of the rim.
So basically.. If you increase the mass, it'll be harder to start rolling the rim, however it'll want to keep rolling farther. Also, increasing the diameter of the rim will have a large effect on how much power it takes to roll the rim. I don't have any equations or definitions to back the next part up, but in my opinion, the tractive forces from the tires and the power needed to overcome friction on the road is going to be much higher than that needed to spin the wheel, so most likely a change in mass and/or diameter will NOT make a huge difference. Just thought i'd toss in my info so you guys can understand and make your own decisions.