OBS Chevy Prerunner Fenders & Fiberglass Bedsides

July 26, 2026

The short answer: a wide-stance OBS Chevy prerunner runs fiberglass front fenders and bedsides in place of the steel, because bigger tires and more suspension travel need clearance the factory sheet metal can’t give. On the 1988–1998 GMT400 the standard sizing is about +3" wider front fenders and +4" wider bedsides, and the OBS is unusually well supported here thanks to its huge street-truck following.

Why an OBS prerunner runs fiberglass

Three reasons: clearance for wider track width and taller tires, weight (fiberglass is far lighter than steel), and replaceability — when the desert eats a panel you’re out a fender, not a fender and the metal behind it. You also get the wide, aggressive stance that defines the look. For the full breakdown of finishes and fitment, see our prerunner fiberglass fenders & bedsides guide.

OBS fiberglass sizing: +3" fenders, +4" bedsides

The common OBS offerings widen the front fenders roughly 3 inches per side and the bedsides about 4 inches, which clears the bigger tires and long-travel front geometry a prerunner runs. Some makers also sell a "conversion" fender that gives the later 1999–2006 front-end look on an 88–98 truck. Panels are hand-laid and typically ship in raw gelcoat, ready for bodywork and paint.

Who makes OBS (1988–1998) fiberglass

Two companies make dedicated 88–98 GMT400 off-road fiberglass:

  • McNeil Racing — a full 88–98 line: roughly +3" bulge front fenders, a +4" "conversion" fender, and +4" bulge and TT-flare bedsides. Hand-laid and finished ready for paint. See McNeil’s 88–98 fiberglass.
  • ADV Fiberglass — 88–98 Silverado fiberglass front fenders with a ~4" flare / 3" rise (part AFC 16), hand-laid in the USA with a carbon-fiber option. See ADV’s OBS fenders.

One thing to know: some big desert-fiberglass names (like Fiberwerx) start their Chevy line at 1999 and don’t make OBS parts — so stick with makers who list 88–98 fitment.

Fitment and finishing

Hand-laid glass is never truly bolt-on: plan on trimming, drilling your own mounts, and bodywork before paint. Most builders run raw/gelcoat, pre-painted, or a Line-X-style coating for a durable satin finish. Our fiberglass guide covers the raw-vs-painted-vs-Line-X tradeoff in detail.

OBS fenders FAQ

How much wider are OBS prerunner fenders?

Typically about +3 inches per side up front and +4 inches on the bedsides — enough to clear bigger tires and a wider, longer-travel front end.

Do I have to run bedsides if I do the front fenders?

No, but most builders match front and rear so the stance looks intentional. Wider front fenders with stock bedsides can look mismatched once the truck sits on a wide track.

Who makes fiberglass for an 88–98 OBS?

McNeil Racing and ADV Fiberglass both offer dedicated 88–98 GMT400 fenders and (for McNeil) bedsides. Verify 88–98 fitment before buying — some brands only start at 1999.

More OBS & prerunner guides

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