Aftermarket extensions added to the wheel arches to accommodate wider wheels and tires than the original body would allow.
Fender flares are extensions added to vehicle wheel arches to accommodate wider wheels and tires than the original body design allowed. Flares may be bolt-on plastic or fiberglass parts (the most common), riveted aluminum or steel fabrication (Liberty Walk and similar widebody styles), or hand-fabricated steel that is welded to the existing fenders (more permanent, often used in restomod and high-end modification work).
Common fender flare types include subtle bolt-on flares (1-2 inches of additional width per side, popular in OE-style upgrades), aggressive bolt-on flares (3-6 inches of additional width per side, popular in stance and tuner applications), and full widebody fender extensions (Liberty Walk, Rocket Bunny styles, often with riveted hardware). Each style has different visual character and complexity of installation.
Fender flares allow wider wheel and tire combinations than the stock body permits. The visual benefit is aggressive stance, with wheels filling the wider wheel arches. The functional benefit is the ability to fit performance tires (wider tires for better grip) without rubbing on the fenders during compression or steering. Quality flare fitment depends on proper alignment with the original body, complete sealing against debris and water, and correct installation of mounting hardware.