I still say the easiest way to give optimus a trailer without going through all the roller and mass shrinking problems would be to simply make it a hologram.
well, since prime was an older model peterbilt, i say magnus should be a late model one.
two cents...
i don't see a logical point of the trailers... unless the trailers themselves transform into something functional. a mobile base perhaps? or sam and mikaela's boink spot... BOOYAH! when the trailer's a-rockin'...
What're the chances of TF 2 having actual "beast" TF's? I mena, not just Beast Wars bots, but just animilistic bots, like Ravage. It would be nice to see a four-legged bot kick ass besides Scorponok who didn't do much for himself in the film IMO.
Ahh,you know what? It was the "Transformers:Robots in Disguise" animated series that aired a couple of years ago on Fox,but I looked it up on Youtube and it turns out that's the one where Optimus is a Fire Truck.(Fire Convoy)
Basically Optimus is the fire engine itself,so he disconnects from the rest of the fire truck and transforms into his robot mode.And if the situation calls for it,Optimus then combines with the rest of the fire truck to become a big bot.
But it's essentialy the same concept,so they can apply the same idea to the next movie when Optimus is hauling his trailer.
Also,Transformers:RiD is the series where (I think...),Ultra Magnus combines with Optimus to form "Omega Prime".
Robots in Disguise(RiD) Was an awesome re-incarnation. It introduced Scourge(Black Convoy) and a somewhat double-crossing Ultra Magnus. The bots were cars, and Beast Wars-like Predacons were included. A great spin-off imo.