Products from the pyrolysis of tire-derived fuels (TDFs) were investigated with various analytical techniques and under various final pyrolysis temperatures and heating rates. The pyrolytic products are classified as char (solid product), pyrolysis oil (liquid), and gas. Principal functional groups of the TDF and pyrolysis oil were confirmed by a Fourier transform infrared spectrometer, coupled with attenuated total reflectance (FT-IR/ATR). The byproducts in the pyrolysis oil fraction were individually quantified using gas chromatography coupled with mass spectrometry (GC-MS). The major products are one- and two-ring methyl-substituted aromatic isomers. Byproduct formation mechanisms of TDF pyrolysis were hypothesized based on the products identified. The mechanisms for aromatic hydrocarbons formation were found to be associated with polymer degradation, methyl displacement, and the Diels-Alder reactions. Our study indicated that GC-MS coupled with FT-IR is sufficient to investigate the semivolatile and volatile organic species from the decomposition of complex polymeric materials such as tires.