Pt-Rh alloys have been successfully used at industry in glass-making for almost a century. However, the price of Rh has exponentially increased in the past few years, a factor that has stirred industrial concern. Consequently, this sparked a search for alternative Pt-based alloys that can offer similar properties. In this quest, the current study deployed the density functional theory (DFT) based first-principles CASTEP code embedded within the Materials Studio software package to investigate the effect of alloying Pt with ruthenium (Ru) and iridium (Ir) on structural, thermodynamic and elastic properties using a supercell approach. The resulting properties of the Pt-rich solid solution alloys are compared to those of commercial Pt-Rh alloys used in the glass industry. Although the addition of both PGMs results in solid solution strengthening, it is evident that the rate of strengthening is much slower in Ir-alloyed compositions as compared to Ru-alloyed compositions. On the other hand, the Ru strengthening rate is found to be much more rapid than even rhodium (Rh). Using this approach, it was possible to identify Pt-Ru (≥9.374 at. % Ru) and Pt-Ir (≥12.5 at. % Ir) compositions that have mechanical properties that match those of the commercial Pt-Rh alloy.