Firestone's rhymes with:
blackstone's, bridgestone's, cherrystones, cobblestones, cornerstones, flagstones, folkstone's, gallstones, gemstones, gladstones, gravestones, hailstones, headstones, keystone's, keystones, limestones, livingstone's, madstones, milestones, moonstones, redstone's, rhinestones, tombstones, waterstone's, yellowstone's
Firestone's sounds like:
fabricating, fabrications, farsightedness, forecasting, foreshadowing, forgetting, fractions, frictions, frightening, frightens, frosting, frostings