2x6 lumber should never be used for joists that span open air. Even on a deck. They're fine for fully supported floors, such as with full-contact rock or gravel bed foundations.

Then, it's not so much a matter of lumber size, but of footing interval. I'd use 2x8 for the whole thing, with the common joists on 16" centers (partially for structural reasons and partially to give you flexibility in decking).

Since you're using single rim joists (to fit the footings), I'd use four footing blocks on each of the 10' sides. This will ensure stiffness appropriate for the load of the common joists. There's really no reason to use more on the 8' rims, as they don't carry any more than the common joists in the middle.

I won't quote load tables or the like. I'm speaking from 30 years of construction experience. If you're going to need to pass inspection, run your plan by your city office for review.

2x6 lumber should never be used for joists that span open air. Even on a deck. They're fine for fully supported floors, such as with full-contact rock or gravel bed foundations.

Then, since you're using those footing blocks it's not so much a matter of lumber size, but of footing interval. (You can't double the rim joists.) I'd use 2x8 for the whole thing, with the common joists on 16" centers (partially for structural reasons and partially to give you flexibility in decking).

Since you're using single rim joists (to fit the footings), I'd use four footing blocks on each of the 10' sides. This will ensure stiffness appropriate for the load of the common joists. There's really no reason to use more on the 8' rims, as they don't carry any more than the common joists in the middle.

I won't quote load tables or the like. I'm speaking from 30 years of construction experience. If you're going to need to pass inspection, run your plan by your city office for review.