Dunlop Develops New GT503 For 2021 Harley-Davidson Sportster S

A performance Sportster calls for performance tires.

By: Dustin Wheelen

Aug 11, 2021 at 12:33pm ET

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Dunlop has supplied original equipment and replacement tires for several Harley-Davidson models since 1984. Despite the long-time relationship, most previous-generation Sportsters wore Michelin Scorchers from the factory. When the Motor Company unveiled the 2021 Sportsters S, it upped the performance ante with the firm’s Revolution Max 1250T engine hanging from the new three-piece trellis frame.

Of course, all that power doesn’t mean squat if you can’t get it to the ground. So, Harley-Davidson turned to Dunlop to formulate a bespoke tire for the next-generation Sporty: the GT503. With the Revolution Max 1250T pumping out 121 horsepower and (more importantly) 94 lb-ft of torque, the platform needed a hoop that could hook up off the line and out of the corners.

The old bias construction wouldn’t do the trick, so Dunlop developed a new radial tire equipped with its Steel Jointless Belt (JLB) technology. The 160/70R17 front and 180/70R16 rear tire provide ample stability with a generous contact patch, but the new radial carcass also delivers an ultra-compliant ride.

The GT503’s round profile contributes to the Sportster S’s responsive yet predictable handling and the new compound achieves grip levels rarely achieved on Sportsters of yore. The aggressive tread pattern and water sipes should also preserve traction in wet conditions.

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"We are proud that Harley-Davidson has chosen Dunlop as original equipment for the Sportster S,” proclaimed Dunlop Europe Marketing Manager Luca Davide Andreoni. “It has been exactly 40 years since Dunlop was asked to develop OE tires for the first Sportster. Since then, Dunlop has supplied over 10 million tires of original equipment to Harley-Davidson, proof of our close collaboration. With the Dunlop GT503, Dunlop continues to develop innovative tires to meet the needs of the manufacturer and its customers."

Luckily, we’ve tested the Dunlop GT503 first-hand on the new 2021 Sportster S, and the new tires didn’t disappoint. Dunlops may not have been on the previous-generation Sportsters, but we have a feeling they’ll be on future iterations for decades to come.