Guys, this has been talked about over and over and over.
Just as Marek said: you won't tow a 50-ton tank out of a ditch or fallen house in one turn's real-life equivalent, let alone move it to anywhere.
Of course one could hack the OOBs to come up with ARVs, and AFAIK that has been done now and then.
Why this is and apparently will remain a no-go for the official version goes as follows: (beside the time issue)
So you get your ARV with carry capacity 255 to tow away the heaviest tanks. With any luck you can use it to take away stuck AFVs, providing it doesn't get stuck itself and said AFV comes unstuck when you unload it (well duh, looks like the "immobilized" aka "speed=0" is written into the unit's data no matter what, but that remains to be checked).
Now, supposing all the above conditions are met and your ARV is functional, what on earth should prevent you from isung it as a super-battletaxi?
It is mobile, armored, and you can stuff it as full as a landing craft! You'll tell me, that's what player rules are for, but then you'd better make these ARVs designer-only access (e.g. modify tehn inside scenarios).
And if ever you put them in OOBs, make even more damn sure that they don't fall into IA hands, because the IA doesn't understand nothing to player rules.
This being said (or ranted...), there's this nice shiny and underused "tank transporter" class the IA isn't ever going to use, so if anyone here has OOB space and time to waste to try this out, lt us knoy if it works!