What do you define as lower tier?
Here's another question? How did you qualify a program for being higher tier? Did you use the US New Reports list of best Rehab Hospitals as part of your process for 'ranking' programs?
Mog16 is absolutely right; you can't tell a program from its cover. You can only tell by going there yourself, talking with attendings, talking to residents, doing YOUR OWN research. What are the didactics like? What exposure to procedures will I get? Will I have a balance of inpt and outpt physiatry? What is the boards pass rate? Where have your *successful* residents gone to for jobs or fellowships (Notice I said successful; you can go to the best program in any specialty but if you are terrible you are terrible and your program director will not endorse you).
Having said that, there are programs that are lower tier in the sense that they use residents as half price PA's/Np's. If you see that, Run, do not stick around.
Fun fact, a few weeks ago I just got mailed by the survey folks that run US New' Best Hospitals issue to provide what I thought was the top 5 rehab hospitals in the US. All I'll say is its a very unscientific process and the voting process reminds me of a popularity contest that is propagated by what you probably remember as the US news best 5 in distant years. I was pretty cynical about US News before, and I am even more now. Furthermore, the quality of a rehab hospital has very little correlation with the quality of an associated residency program except maybe how strong you will be in brain injury or SCI training - and that depends on how much your attending is willing to teach.
Disclaimer: I went to one of the 'Super 6' programs that ppl on this board use here all the time. I have met in almost 10 years out from residency, plenty of folks from a variety of training programs. I cannot say that I am more 'Super' than any others. I think we're all trained the same. Go to a solid program that you think fits your personality and lifestyle. You'll be fine and nobody really makes a big deal of this.