Tire wear particles can form via two distinct pathways-mechanical abrasion and evaporation-condensation-resulting in aerosol particles with different size ranges and chemical signatures. This study investigates the volatile submicron fraction produced via evaporation-condensation by generating seed-coated aerosols from seven tire materials in a tube furnace and characterizing them using a soot-particle aerosol mass spectrometer (SP-AMS) coupled with SMPS measurements. Across all tires, particle growth onsets occurred at T go approximate to 144-163 degrees C and new particle formation associated with high-temperature "smoldering" at T so approximate to 178-200 degrees C, with systematic differences between passenger-car and heavy-duty tires. The composition of the volatilized tire-derived aerosol particles was dominated by hydrocarbon fragment ions (e.g., m/z 41, 43, 55, 57, 69) with a distinct aromatic contribution at m/z 91 (C7H7 +), and the particles also contained oxygenated fragments at m/z 60 and 73 that are commonly attributed to biomass burning, highlighting potential source-attribution ambiguity in urban environments. Comparison with mechanically generated tire dust showed enrichment of unsaturated and higher-mass hydrocarbon fragments in the non-volatilized material, consistent with lower volatility. These results provide reference SP-AMS signatures and temperature-dependent indicators for volatile tire-derived submicron aerosol and support interpretation of laboratory and ambient measurements of tire wear emissions.
