Thermal and catalytic coprocessing of waste tires and coal was performed using waste tires from two sources and coals of three different ranks. Bituminous coals yielded higher conversions than either subbituminous coal or lignite when coprocessed with waste tire. In this study waste tires from tire buffing processes were used. One of these materials provided by Rouse Rubber represented the typical composition of most automotive tires while the other material supplied by Uniroyal contained a substantial amount of mineral fillers because the material obtained from buffing the white lettering on the sidewall of the tire. Each of these waste tires when used as a solvent in coprocessing had different solvent qualities; the Rouse waste tire was typically a much better solvent for coal than Uniroyal waste tire. Catalytic coprocessing of waste tires with coal using slurry phase hydrogenation catalysts increased total and coal conversions compared to thermal reactions. Addition of carbon black to the coprocessing system had minimal effect on the conversion or product distributions, while the addition of the heat-treated residue from the liquefied waste tires resulted in enhanced conversion and hexane solubles production from coprocessing systems. The mineral-rich Uniroyal residue was more active than the carbon black-rich Rouse residue. Combining the residues with slurry phase hydrogenation catalysts enhanced their activity even further.