Vinyl seat dye???
I used SEM to dye white seats black. It held up for two years (20kish miles) until the stitching started to fail and I purchased new seat covers.
The only place it would wear off is the is the piping on the edge of the seat where I slide my but across every time I got in/out. A quick clean and respray once or month would take car of it.
You can get SEM products on line from Eastwoods or at any Autobody supply store.
NOTE: you need to clean, clean, clean and clean some more then use the SEM vinyl prep. Any cleaner with ammonia will work, I used 409.