Fixed-bed reactors for steam reforming of methane (SRM) operate under high pressure, temperature, and Reynolds numbers. In this study, the entrance region of a SRM fixed-bed reactor is simulated with particle-resolved computational fluid dynamics (CFD) simulations under two flow conditions (Re-p = 755 and 7554). Thermal radiation effects are modeled in detail by surface-to-surface (S2S) radiation and energy-absorbing gas-phase species (discrete ordinate method (DOM)). Taking radiation into account leads to an increase in local temperatures of up to 40 K and to a total hydrogen production 70% larger than that found by neglecting radiation. However, the DOM and the S2S model do not show large differences in local temperature and gas-phase composition prediction. The comparison of computational costs gives a recommendation for modeling thermal radiation in packed beds: the S2S model is to be preferred over the DOM radiation model, which need 7.5% and 35% additional calculation time in comparison to the model neglecting radiation, respectively.