I have on '08 FLHX with a Sundowner seat. Ride to work most days, so the bike sits in the sun a good bit. After 35K miles, I found a small tear in the seat. Repaired it. Developed another one in another place, then two more. Looks like the vinyl is tired from the heat. I have the new seat - but want to know before I put it on what others are doing to care for your seat. Vinyl treatment of some kind? Leather care products? Cover? I don't really want a full cover, but I've considered a seat cover of some kind.
If I have to replace the seat every 35K so I can enjoy riding every day, that's better than driving my Tahoe to work - but thought I get some ideas.
I suspect it's not so much the heat as it is the ultraviolet rays of the sun attacking the material. How about keeping it covered while in the sun? Just a thought...
I would just drape a towel over it while it sits at work. Will protect the seat from sun and rays and also keep it a bit cooler when you go to sit on the seat.