Will 245/75/16 tires fit on my stock 2009 Hummer H3 rims?
They should fit just fine. Here is a site where you can get tires in that size that will fit your Hummer: http://www.tirerack.com/tires/TireSearchResults.jsp? customSizeSearch=true&autoMake=Hummer&autoYear=2009& autoModel=H3&autoModClar=Base&width=245%2F&ratio=75& diameter=16
The original tire size that your truck uses is a 265/75/16. So 245/75/16 will be slightly smaller in width but should be fine.
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