Theirs rhymes with:
there's, affair's, affairs, air's, airs, ayer's, ayres, bancshares', bares, bear's, bears, bears', berres, billionaires, blair's, blares, bures, care's, cares, chaires, chairs, claire's, compares, d'affaires, dares, declares, despairs, downstairs, ensnares, errs, euromobiliare's, fair's, faires, fairs, fares, flares, freres, frontieres, gehres, glares, hair's, hairs, hare's, hares, heirs, impairs, jares, kehres, maerz, mairs, mare's, mares, millionaire's, millionaires, moliere's, multimillionaires, pairs, pares, pears, phares, pierre's, prayers, prepares, questionnaires, repairs, sayres, scares, share's, shares, shares', sherr's, snares, spares, squares, stairs, stares, swears, tears, there's, unawares, upstairs, usair's, wares, wears, where's
Theirs sounds like:
tadros, tara's, taras, tariq, tarkowski, tarses, tarsus, tatars, tatters, taurus, tauruses, tears, tedrick, teeter's, teeters, terasawa, teresa, teresa's, terese, teresi, teressa, terex, tereza, tereza's, teriyaki, terra's, terrace, terraces, terrasi, terrazas, terriers, terris, terrizzi, terrorize, terrorizes, terrors, terry's, terse, teruko, teters, tethers, tetrick, thayer's, thayers, theater's, theaters, theatre's, theatres, theatric, theatrics, theodric, theories, theorize, theorizes, theory's, there's, theresa, theresa's, therese, theroux, thirza, thoracic, thorax, thorough, thrash, thrashes, three's, threes, thresh, thrice, throes, through, throughs, throughway, throwers, throws, thrush, thrushes, tiaras, tidrick, tierce, tierco, tiers, tires, tiros, torch, torches, torchia, tories, tories', torok, torque, torras, torres, torrez, torrijos, torrisi, torso, torsos, touareg, tour's, tours, tower's, towers, towers', trac, trace, traces, tracey, trachea, traci, tracie, track, track's, trackage, tracks, tracy, tracy's, tracz, traczyk, tragic, tragos, trak, trakas, trash, trashes, trashy, trask, traugh, trausch, traweek, trawick, trax, trays, traywick, treacy, trease, treece, trees, treese, treesh, trego, trejo, trek, treks, tresch, tress, tresses, trezise, trezza, triage, triarc, triassic, trice, triche, tricia, tricia's, trick, trickey, tricks, tricky, trico, tries, trig, trigg, triggs, trigo, trio's, trish, trisha, trisha's, triska, trixie, trixy, trizec, trizec's, troche, trocki, troika, trois, troise, troisi, trosch, trough, troughs, troyka, truax, trucco, truce, truck, truck's, truckee, trucks, trucks', truex, truicko, trus, truskowski, truss, trusses, truszkowski, trygg, trzaska, trzeciak, tudor's, turchi, turck, turco, turek, turk, turkey, turkey's, turkeys, turkic, turkish, turko, turks, turowski, turquoise, tursi, turski, tutors, twarog, twersky, tworek