Hi Chris ,
RadTileList mimics the Windows 8 start menu and thus tiles flow down then to the right.
In case you need the tiles to go to the right, you can consider standalone tiles: http://demos.telerik.com/aspnet-ajax/tilelist/examples/standalonetiles/defaultcs.aspx. From a layout point of view, they are divs with float: left and display: inline-block. You can generate them programmatically by looping through your data.
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