Firestone radial tire sidewalls aren't very forgiving on tubes.  A few years ago we run over a shed antler while brushhogging and had to put a boot on the sidewall of the tire.  The tire guy's recommendation was to use a tube inside the tubeless tire to help "pressure cure" the boot to the sidewall. 

Curing the boot to the sidewall worked, but the tube was shot in about 60 days due to the constant flexing of the sidewalls and the small "ribs" inside the Firestone radial. 

Your rims, if clean and in good shape, should be just fine having tubeless tires mounted on them.  As referred to above, the tire type (tubeless or tube-type) dictates the way they are used, not the rim.