screen door roller assembly, 1.5 inch steel BB roller. concave

Can you confirm that this is for a screen door? That must be some heavy duty door. The roller you have here is most commonly seen on glass doors. Either way, I think our 81-009 is a promising match. It's very similar to your dimensions and I think will work well as a replacement. You may want to look over our measurements just to be sure.

The question of using a nylon or steel wheel is something I personally go back and forth with. Steel wheels are obviously stronger but they can wear out the track sooner. They're also more susceptible to corrosion. Nylon wheels don't have either of those issues, but they will break sooner. It's pretty much a matter of whether you'd rather replace a track or a roller 15 years from now.

Looking at your roller myself and considering your dimensions, I'm thinking that maybe the 81-032B might be a better match. Check it out and let me know what you think.