This work gives a rigorous proof of the existence of propagating traveling waves of a nonlinear reaction-diffusion system which is a general Gray-Scott model of the premixed isothermal autocatalytic chemical reaction of order m (m > 1) between two chemical species, a reactant A and an auto-catalyst B, A+ mB. (m + 1) B, and a super-linear decay of order n > 1, B. C, where 1 < n < m. Here C is an inert product. Moreover, we establish that the speed set for existence must lie in a bounded interval for a given initial value u0 at -8. The explicit bound is also derived in terms of u0 and other parameters. The same system also appears in a mathematical model of SIR type in infectious diseases.