WIDEST, not tallest, tire stock
 

Tried this in the Superduty section, but no one knew.

What is the widest 33 i could mount on the stock 17 inch wheels on my truck?
Its a 07 350 XL, PSD, FX4 with the heavy service front springs. Its got the factory 265s on it now.

I wouldn't go wider than a 305/65-17 (33x12.50) on the oem wheels.

I agree, any more than a 12.50 would be a pain to mount. Plus, if you ever we're to air down to go offroad, you would probably blow a bead.

i agree with wandell too. on a stock rim. plus the backspacing it might rub even at 12.5.

would it be rubbing on the radius arms or suspension, or would that be bumper rub?

With the oem wheel, if you had any rubbing it would probably be on the radius arm. However, I've seen several stock SD's fit 35x12.50's on oem wheels so I doubt you will have any rubbing at all with 33's.
Also, you are LESS likely to pop a bead with a wide tire on a narrow wheel.