Forum Please explain the three sitemaps
 

I have three sitemaps, the largest one vbulletin_sitemap_thread_1_2276.xml.gz,cannot be read:

Quote:
The document “vbulletin_sitemap_thread_1_2268.xml” could not be opened. Text encoding Unicode (UTF-8) isn’t applicable.

What should I use in Google Webmaster tools, all three or just the

vbulletin_sitemap_index.xml.gz (the large one also keep changing name)

???

Thanks