I'm running a full width 90' D60 up front and a stupid wide D70 out back. You think the D60 drags, lol, it's got nothing on my wide D70. I've got a narrower D70 that I just need to swap my hubs and brakes over to, but I don't need to do that yet. I'm running on 37" tires.
One of the best advantages to full widths is the leverage on the springs - it's like in-boarding your springs for a LOT of articulation.
It would have gone further, but the tire is throughly planted into the inner fender.