I've read a number of sites that caution not to deviate from the manufacturer's offset number on wheels.

Aside the rubbing possibility - is there a safety concern? it seems like a an inch or two difference wouldn't matter a lick....

Can anyone educate me? Thanks.

 

No safety issue at all. They caution against it to avoid rubbing issues I believe. On my lifted f150 I run a 20x10 -24 offset. They stick out quite a lot. It does put more wear and tear on wheel bearings but you'll still get good life out of them. On my super duty I'm running an 17x8 with zero offset and the tires are under the truck just like stock.