A method to know how much the thermogravimetric data are close to the Arrhenius-type rate equation was suggested. By using this method, pyrolysis of lignite that did not soften or swell with increasing temperature was proved to be well explained with the Arrhenius-type rate equation. On the other hand, pyrolyses of thermoplastics such as PS were far from the Arrhenius-type rate equation due to the significant melting and swelling with increasing temperature. Pyrolytic propensity of tire chips was between those of lignite and thermoplastics but was still distant from that expected by the Arrhenius-type rate equation.