Well I've lurked around here long enough without contributing, so here we go:
That used to be a common problem on '70s vans with wheel flares. Aftermarket brackets were made to extend the door out further when opened.
(see this link for an example-http://www.bkauto.net/ateamadditionalparts.htm )
The 2010 Express (we use about 30 of them where I work) has a radically different slider design, so I don't think the old style bracket will work. It looks like moving the external track away from the body to clear the tires might work. You would have to remove the interior panel to access the bolts, push the track out and put some washers or spacers on the bolts between the track and body to move it out. If that works, you could even put the inside panel back on the door.