Can anyone recommend the size of the backing line for an 8wt reel?

I have 20 lb. backing line on the reel now for when I fly fish for bass.

Also, what size fly line and leader should I use to catch these Steelheads?

Thanks,

I grew up in Oregon, fishing for trout salmon and steelhead. I used to tie my own tapered leaders, and would end it with 12lb maxima camelian mono. As long as your leader is less than your backing you are good.otherwise you run the risk of loosing you fly line.

20 lb backing should be fine, though you will want a reel with a good disk drag and enough capacity in the spool for at least 200 yards of backing. Unlike bass, steelhead can really tax a lower quality reel with a poor drag system.

Rio makes specialized tapered leaders for steelhead and salmon. Most are 9 to 12 feet in length and tapered to 1x or 0x.

Rio also makes a Salmon/Steelhead fly line. I just purchased one in an 8wt for an upcoming Alaska salmon trip. It casts fine on a standard 9ft 8wt rod (mine is a Sage Xi2).