This study examines the phonetic properties of lexical tones in Singapore Teochew (SgT). An acoustic analysis of 18 speakers’ tone production using generalised additive modelling reveals variations in both pitch height and contour shape for SgT compared to the variety spoken in China. Specifically, the mid-level T1 and high-level T2 are generally flatter and exhibit a more level contour in SgT. The high-rising T4 in the Singapore variety is significantly lower and displays a dipping contour not found in Standard Teochew. Additionally, the low-dipping T5 and low-level T6 are merged into a falling tone in SgT. By comparing the tone production of SgT speakers with that of English-Mandarin bilinguals, this study suggests that transfer from Singapore Mandarin is likely to be a significant factor in shaping the overall tonal variations in the local Teochew variety.