Fender Trimming and Flares for Tire Clearance

Difficulty 3/53–8 hrs$40–4001966-1977

Lift gets the tire room to droop; fender trimming gets it room to stuff. If your early Bronco rubs at full compression or on tight turns even after a lift, the fender opening is the limit, not the suspension. Trimming sheet metal and adding flares is how you clear 35s and up without slamming the tire into the body on every dip.

A lift creates static clearance, but a tire moves through its full travel under load. When the suspension compresses over a bump or in a turn, the tire moves up and back into the fender. That is where rubbing happens — not while parked. Trimming removes the metal the tire contacts at full stuff, and flares cover the wider stance and protect the body from trail debris.

Cutting sheet metal is permanent, so map the contact zone first. With the truck on the ground, turn the wheels lock to lock and watch where the tire approaches the fender. Then cycle the suspension — drive a wheel up onto a ramp or curb, or disconnect a shock and stuff the tire by hand — and mark every point of contact with tape.

The marks show the cut line. Add a margin so the tire clears under full articulation with a flexing sidewall, not the bare minimum at static height. A tire that barely clears on the bench will rub on the trail.

Work in stages. Mark conservatively, cut, re-check clearance, and trim more only if needed. You cannot put metal back.

Use a cutoff wheel for the main cut and a flap disc or file to dress the edge smooth. A raw cut edge is sharp and will rust, so finish it: file it clean, hit it with self-etching primer, and seal the edge with paint or pinch-weld trim molding. On an Arizona truck rust is slower, but bare steel still corrodes at a cut edge.

A cutoff wheel is fastest for a straight-ish cut but throws sparks and leaves a rougher edge than a jigsaw with a metal-cutting blade, which follows a curved line more cleanly but needs a pilot hole to start and takes longer. When a flare is going to cover the edge, speed wins -- take the grinder. When the cut stays exposed, as with a mild lip trim and no flare, take the slower jigsaw route and put the time you saved into filing, since that edge is what people actually see.

Aftermarket flares serve two purposes: they cover the wider track of a lifted truck with offset wheels (often required to keep tires legally covered), and they protect the body from rocks and mud the wider tire throws. Early Bronco flare kits bolt or rivet to the trimmed opening. Match the flare width to how far your tires stick out past the body — too narrow and the tire is still exposed, too wide and it looks unfinished.

Most trimming discussion, and most flare kits, center on the front fenders, since turning the wheels adds lateral tire movement on top of suspension travel. The rear wheel wells only see vertical travel, so they typically need less trimming for the same tire size -- but check them anyway. A wheel pushed outward by wheel spacers or a wider aftermarket wheel with less backspacing can rub the rear opening even with modest suspension travel. Measure both ends before you buy a kit; some flare kits are front-only and pair a narrower rear flare or none at all, which won't help if the rear turns out to be the tighter fit.

Many states set a minimum fender coverage requirement -- commonly that tire tread can't extend past the body or flare by more than a set distance, though the exact figure and how it's measured varies by state. A wide tire on a trimmed, unflared fender can put you outside that limit and draw an equipment citation independent of anything else on the truck. If you're trimming to clear a genuinely wide tire, budget for flares wide enough to actually cover it, not merely wide enough to stop the rubbing you have today.

The most common mistake is cutting to static clearance and discovering rub on the first trail run. Always check at full compression and full lock, not only sitting level.

The second is leaving raw edges unsealed. A cut fender edge is the fastest place for rust to start on an otherwise solid truck. Prime and seal every cut.

If you run 33s on a moderate lift, you may not need to cut at all — a mild trim of the inner lip or a pinch-weld roll can be enough. Save the angle grinder for when the tire actually contacts paint.

Budget $40 if you are trimming and sealing bare metal, $400 for a full flare kit painted and installed. The work itself costs little — the value is in measuring carefully so you cut once.

Tools required

Parts

PartVendorEst. price
Aftermarket fender flares (early Bronco set)Various~$280
Edge trim / pinch weld moldingVarious~$30
Self-etching primer and paintVarious~$35

Sources

Related


Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.

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