From Japanese-English FreeDict Dictionary ver. 0.1:
(ateji (phonetic) reading) [ichi1] 屯 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, (ateji (phonetic) reading) 噸 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, (ateji (phonetic) reading) 瓲 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, [ichi1] トン /tˈo̞ɴ/
(noun (common) (futsuumeishi))
Note: word usually written using kana aloneton (now usu. a metric ton, i.e. 1,000kg), tonne