As was previously mentioned forged wheels are typically just lighter than cast wheels. Forged aluminum has a higher strength than cast aluminum, however manufacturers tend to use this to just make the wheels lighter rather than stronger. Since weight is a nice advertiseable spec, manufacturers like to make the wheels as light as possible. Durability is much harder to measure, and thus they can't advertise it as well. What you really want to prevent damage from potholes is a bigger sidewall on the tire. Although a fairly light car like the roadster you can get away with a pretty small sidewall. Course if you're talking about a big ole Cadillac, in a Tesla forum, just get smaller wheels.
Correct for the front, not so much with the rear of the Roadster. The rear suspension doesn't have much travel either let alone the majority of the weight is back there.
Heh sorry about that; this thread is a top Google search result for "alloy wheels cast vs. forged" Anyway 18" wheels would probably be better in my case but not when you consider the size of the potholes we get like the one in the pic I posted. Plus 20" wheels look a lot better.
The Holy Grail of Tesla wheels ... OEM forged Arachnid rims just like Elon's Model S New Tesla Factory Model S 21 inch Arachnid Wheels, Limited Edition
I currently have cast wheels on my roadster and my tire life is significantly longer than when I used forged wheels! So with the lighter forged wheels you probably get a little more wheelspin/acceleration which wears your rears but then again I could be driving like a granny now
^ Well this goes along with my theory on how / why I can milk the miles I do out of my rear AD0x tires by not punching it off the line but rolling it a bit. I feel there's some slip of the wheel where its in effect like a plane coming in for a landing on a runway. The heavier the wheel is the less snap it has.