It's not accurate. My 91 Burb came factory with 29 x 8.5 stock. and yes, it's 4x4
The table is not listing what size tires came stock on a Blazer/Jimmy/Suburban, it is simply showing the largest tire that will generally fit and what modifications would be needed to fit that tire.
So the first row with 31x10.50 stock, simply means that a 31" tire will fit on a stock Blazer/Jimmy/Suburban without modification, not what size tire it came with from the factory.
Separate names with a comma.