An Etymological Dictionary of the German Language/Annotated/Rad
Rad, masculine, ‘wheel,’ from the equivalent Middle High German rat (genitive rades), Old High German rad, neuter; corresponding to Low German and Dutch rad (compare also Old Frisian reth). The word is confined to Middle European Teutonic; it is wanting in English, Scandinavian, and Gothic; this, however, is no reason for assuming that the word is borrowed from Latin rota. Since Old High German rad is based on pre-Teutonic rotho-m, rothos, neuter, (Gothic *raþa-), ‘wheel,’ it is primitively cognate with the equivalent Old Irish roth, masculine, and Latin rota, and likewise with Lithuanian rátas, ‘wheel.’ The corresponding Sanscrit ratha-s (rathas, neuter in ráthas-páti) signifies ‘car,’ especially ‘war chariot’ (for the root roth see under rasch), while Sanscrit cakra, Greek κύκλος, corresponding to Anglo-Saxon hweol, English wheel, also means ‘wheel’ in Aryan. —