Sinking Tip Line for Steelhead?

I don't think they are necessary in PA Erie tribs.
 
There are some places where one could be useful in Ohio and NY, I've not used them though.

If you're looking to fish streamers in strong flows, they are beneficial.  I like using a 2 to 3 foot section with 2x tippet and minimal to no split shot. 

At any point that the tribs are actually fishable, you can still get to the bottom with a floating line, long leader, and lots of shot. Spending money on a sinking line that you'll likely pay $50-$60 for and use only a few times, is not worth it in my mind.
 
Sinking lines are really only good for streamers, since you couldn't mend them to get a good drift with nymphs. I typically nymph for steelies about 99.9% of the time, and don't bother so much with streamers.

Sink tips have their place on the Erie tribs, but mainly for fishing streamers or swinging flies. In my opinion.
 
Even when the water was flowing moderately/perfectly, I needed several density sinking tips last year to reach fish in a 4' deep run on Elk. I started with a type 1, then a type 3, and ended with a type 6 before I started to hook fish. And that was with a big mend and dead drift to get it down before the swing. I could have used a type 9.
 
To figure out the sink rates for the lines, it's the number type plus 1. A type 9 is 9"-10" per second.
 
You can find cheap sink tip lines for under $30 that work great, but I would recommend the Cortland Mini Head Kits. They come in Type 1, Type 3, Type 6, and Type 9 in 12' sections that can be cut down for your preferred length. The kits come with braided loops that can be added to the sections for easy add on and removing. You can cover different sink rates without spending a fortune. I'm pretty sure this is what mgolf is talking about.
 
 
Best,
Fisher

If you guys aren't swinging streamers with a sink tip you're missing out BIG TIME!
 
You give me a pod of fresh fish and water in the upper 50's with stronger flow and I'm tying on the sink tips and swingin' BIG buggers!
 
 I always have sink tips of 2 feet, 4 feet, and 7 feet with me when I think I'll be swinging flies and will change the tips as the depth of the water I’m fishing changes. Dead sticking egg imitiations can get somewhat "regular" after a while, but nothing will get your heart pumping more than a steelie putin' the SMACK DOWN on a streamer swung right in front of its face!
ZZZZZZZZZZZZZZZZZZZZZZZ!!! FISH ON!!!

A couple of years ago I bought a couple of sinking tips that connect to your fly line with a loop to loop system. Orvis I think. I know how much I hate chucking & ducking split shot so I tried these when the need arises. Cast a lot easier and don't get hung up on bottom half as much. I use bead heads for my nymphs and steamers so the weight I do have is at the very end . So much easier and no split shot wrap arounds on the rod tip.

Here is a link that may help.  http://www.flyandfloatfishing.com/flyfishing_videos.htm