I want to start looking for wheels and tires for my new 2500HD. I don't want the tires to stick out real bad past the fender flares. What offsets should I be looking for? Also what is the biggest tire I can run without lifting the truck or major mods??

Not sure on factory offset. But, with 2" leveling keys, I've been told you can run 33"x12.50's (wheels up to 5" backspace, -25mm offset and 10" wide wheel), with trimming of front air dam and rear inner wheel liner.

Factory PYOs have 4 5/8" backspace.

Factory PYOs have 4 5/8" backspace.
I'm sorry but as is PYO?? Most of the wheels I found that I liked where 4 1/2" rear spacing.

I am almost certain the factory PYO wheels are 5.25" offset ...H2's are 5.5" offset.

I am almost certain the factory PYO wheels are 5.25" offset ...H2's are 5.5" offset.I measured mine myself. With a straight edge across the outside of the flat bead area on the back side of the rim, not on the lip of the rim, the distance was 4 5/8" from the mounting surface. According to Petersens 4wheel and Off-road magazine the H2s measure 5 1/8" backspace when measured the same way. The H2s can get away with more backspace due to the 17" diameter.

I'm sorry but as is PYO?? Most of the wheels I found that I liked where 4 1/2" rear spacing.
The PYOs are the forged aluminum wheels that come on the 2500HDs. I'm sure 4 1/2" backspace would fit fine as long as the rim is not too wide. I'm considering a set of Centerline Bullets in 16"x8" with 4 1/2" backspace for my truck.

Does anyone have any pictures of a 16" x8" with a 4 1/2" offset on there 2500HD??