Tumors of various sizes present a challenge in defining the therapeutics parameters to obtain desired thermal damage for plasmonic photothermal therapy. Here, skin tumors of various sizes surrounded by healthy tissue are considered to compute the thermal damage and define the therapeutic parameters. The tumor is assumed to be embedded with gold nanorods which upon NIR irradiation leads to rise in temperature that ultimately results in thermal damage of tumor. To compute the temperature distribution, D2Q9 scheme of Lattice Boltzmann method is used to solve Pennes' bioheat model within tumor-tissue. Radiation absorption by gold nanorods is computed using Beer-Lambart's law for irradiation intensities of 1 and 0.75 W/cm². Also, thermal damage is obtained using Arrhenius equation. Results show that the desired thermal damage is obtained within ~200-300 seconds for shallow tumor while ~480-540 seconds of irradiation is required for deeper tumor. Lower irradiation intensity is favorable to restrict the tumor surface temperature to avoid tissue vaporization.