Weight, under inflation and UV will hurt the tires but most of them blow because of such poor construction. There are several documented reports on various RV websites of these cheap Chinese tires blowing out while mounted on the trailer as spares. How do you explain that other than poor construction? Do yourself a favor and get rid of them. It's just a matter of time....
2015 Chev Silverado 3500 dually D/A
2016 Cedar Creek 36CK
B&W Patriot 18K, Trail-Aire pinbox,
Level up, dual panes & all that stuff...