footings deck 10 x10 foot about 4ft off ground.
 

I just built a deck and used 8 inch sons tubes with 4x4 post. The inspector says I need 12 inch . I live in south jersey is this correct/

More than likely the inspector is right.

What code are you using? Everything I've read says NJ adopted the 2009 awc for decks. Their footings are considerably larger than 12 inches and 6x6 posts

2009 codes thanks I should know the inspector is always right

You probably should discuss all the issues the inspector has with your deck before you fix one issue, then he brings up others. I am guessing you did not file a plan first with the inspector, else he would have flagged the footing size, and the undersized 4x4's. Assuming there was no plan, there could be other issues such as inadequate size of framing members, improper brackets, inadequate railings etc. Might as well get them all out first rather than doing them one by one later.

I think the permit and plans would show that... Oh wait... That's why you always get the permit IN HAND before you start the project...