Abstract: The present invention is based on the discovery that in order for polyester fibers to be used in a polyester/glass mat, which will have superior tear properties after being coated with bitumen, they need to have a single filament toughness of greater than about 140. Toughness being defined as the product of tenacity (in units of cN/tex) and the cube root of the breaking elongation (as a % of elongation). Specifically, the mat has polyester and glass fibers bound together with a binder, and the bound fibers are coated with asphalt. The invention also describes a process by which the web is dried and cured into a mat at a temperature of greater than about 200° C. The polyester is at least about 5 wt. % of the fibers in the coated mat.