I initially had 265s on stock-width 6.5" dually wheels (up front only, rear are 235) and I could feel the sidewall flex. I didn't like it. I ended up swapping out my front hubs so I could run single-style wheels again, allowing me to upgrade to 8" wide front wheels. Huge difference in steering precision and handling. The lower front tire pressure in a Sprinter might allow the sidewalls to flex even more.
2000 E350 extended wagon dually
V10 w/ Banks Powerpack, Diablo Predator
Buckstop Outback bumper/grill guard
Reunel rear bumper