5/16in OD (7.95mm) Hard Line - 25 Foot Spool

The 5/16in OD (7.95mm) Hard Line – 25 Foot Spool is a precision-engineered tubing solution designed for serious automotive builders and mechanics tackling fuel system upgrades, brake line installations, and custom hydraulic applications. Hard line tubing is essential when you need rigid, leak-free conduits that withstand high pressure and vibration in engine bays and chassis where flexible hose won't cut it. This 25-foot spool delivers the length needed for complete system runs without mid-project shortages, making it ideal for street machines, race vehicles, and restoration projects where factory fuel and brake systems require modernization.

Constructed with critical dimensional accuracy, the 5/16-inch outer diameter (7.95mm) hard line is manufactured to handle the demands of pressurized systems—fuel delivery, brake fluid, and coolant circulation all rely on consistent wall thickness and material integrity to prevent failure under thermal cycling and vibration. The seamless construction resists kinking and deformation, which is crucial when routing through tight engine compartments or along frame rails where clearances are unforgiving. Hard line tubing's rigid design minimizes system compliance, reducing fuel return losses and ensuring crisp brake response compared to flex hose over longer runs. At 2.2 pounds for the full spool, the material weight is manageable for installation while retaining structural rigidity.

Professional mechanics and dedicated enthusiasts benefit most from this hard line tubing when building or restoring fuel-injected engines, upgrading braking systems, or creating custom coolant circuits. The 25-foot length accommodates everything from engine bay fuel rail runs to tank-mounted regulator setups without requiring splices. Installation requires proper flaring equipment and adapter fittings—standard AN or SAE flare ends are compatible with this tubing size. Whether you're converting a carbureted classic to fuel injection, installing a modern fuel pump system in a vintage build, or running a custom brake line to a proportioning valve, this hard line spool delivers the rigidity and reliability that separates professional-grade work from amateur shortcuts.