We studied tone-vowel coproduction using Electromagnetic Articulography (EMA). Fleshpoints on the tongue and jaw were tracked while native Chinese speakers (n = 6) produced three vowels, /a/, /i/, /u/, combined with four Chinese tones. We found differences in tongue position across tones for /a/ and for /i/ but not for /u/. The low and rising tones patterned together in conditioning lower tongue blade (TB) position for /a/ and a higher TB position for /i/. This pattern suggests a degree of inter-dependence between tonal and vocalic targets. The effect of tone on TB height was mediated by jaw movement such that, even as TB sensor position varied across tones, the Euclidean distance between TB and Jaw sensors within each vowel remained stable. Thus, for this set of Chinese vowels, there is a relational invariance between active articulators, tongue and jaw. When viewed in terms of this relation, vowel and tonal targets appear to be completely independent.