This study describes the critical speed enhancement of the KTX-Sancheon, a Korean high-speed train, using measured wheel profiles. The wheel wear shape of the commercial high-speed train was measured according to mileage, and the relationship between conicity and mileage was investigated. The critical speed of the KTX-Sancheon power car was analyzed numerically with the measured wheel profiles. The suspension parameters were optimized to increase the critical speed of the KTX-Sancheon. As a result, the critical speed of the power car increased by 34.1% compared to its initial condition. The results are being used for a new design of the power bogie.