Bridgestone S 21 R, 190/55 ZR17 TL (75W), Rear Wheel, M/C, Variant F

Bridgestone S 21 R – The Ultimate Supersport Road Tire for the Rear Wheel

The Bridgestone S 21 R is engineered specifically for high‑performance motorcycles that demand precision, agility, and confidence on both dry and wet surfaces. Designed as a supersport road tire, it delivers exceptional grip, rapid response, and long‑lasting durability while maintaining the lightweight characteristics essential for competitive riding.

Key Technical Specifications

• Size: 190/55 ZR17 TL (75W) – a width of 190 mm, aspect ratio 55%, radial construction with ZR rating for high speed and load capacity.
• Load Index & Speed Rating: TL (75W) – capable of handling up to 750 kg per tire while sustaining speeds up to 300 km/h.
• Construction: Radial, ZR type for optimal stiffness and heat dissipation.
• Type: Supersport Road – tailored for aggressive cornering, rapid acceleration, and high‑speed stability.
• Application: Rear wheel of motorcycles such as the Kawasaki H2, but suitable for any sportbike that requires a lightweight yet robust rear tire.

Performance Highlights

The Bridgestone S 21 R is built around four core performance pillars:

1. Dynamic Traction: The tread pattern incorporates deep, strategically placed sipes that enhance grip during high‑speed cornering and sudden braking. This ensures the rider can push the limits without compromising safety.
2. Rapid Response: Thanks to its low profile and precise sidewall construction, the tire reacts instantly to throttle inputs and steering changes, providing a natural feel that mirrors the motorcycle’s dynamics.
3. Heat Management: The radial design coupled with advanced rubber compounds allows efficient heat dissipation. This reduces the risk of overheating during prolonged high‑speed runs or track sessions.
4. Longevity: Despite its aggressive characteristics, the tire maintains a respectable tread life thanks to a balanced compound that resists wear while still delivering peak performance.

Tread Design and Compound Technology

The S 21 R features a symmetrical tread layout with a central groove that channels water away, reducing hydroplaning risk. The outer edges are reinforced with high‑modulus fibers to preserve shape under load. The rubber compound is a proprietary blend of Bridgestone’s Supersport technology, offering:

• High Flexibility: Allows the tire to conform to road irregularities for maximum contact patch.
• Low Rolling Resistance: Enhances fuel efficiency and reduces fatigue during long rides.
• Abrasion Resistance: Extends tread life without sacrificing grip.

Installation and Compatibility

The tire is available in the standard 17‑inch rim size, making it compatible with a wide range of sportbike frames. It is specifically designed for the rear wheel, where traction demands are highest during acceleration. When installing, ensure:

1. Proper alignment of the bead to avoid uneven wear.
2. Correct inflation pressure as specified by the motorcycle manufacturer (typically between 2.0–2.5 bar for supersport models).
3. Regular inspection for sidewall damage or tread separation, especially after high‑speed runs.

Ideal Riding Conditions

The Bridgestone S 21 R excels in:

• Dry Track Days: Offers maximum grip and stability at high speeds.
• Wet Street Riding: The tread design ensures effective water evacuation, reducing the likelihood of aquaplaning.
• Long‑Distance Touring: While primarily a supersport tire, its balanced compound provides sufficient durability for extended rides on paved roads.

Maintenance Tips

To keep the S 21 R performing at its best, follow these simple guidelines:

1. Check tire pressure weekly; under‑inflation can lead to overheating.
2. Inspect tread depth every few hundred kilometers; replace when it reaches the minimum legal limit.
3. Avoid riding on rough or uneven surfaces that could damage the sidewall.
4. Store tires in a cool, dry place away from direct sunlight to preserve rubber integrity.

Conclusion

The Bridgestone S 21 R 190/55 ZR17 TL (75W) is more than just a tire; it’s a performance partner that elevates the riding experience for supersport enthusiasts. With its advanced construction, aggressive tread design, and proven durability, this rear wheel tire delivers confidence on every corner, whether you’re racing on a track or cruising down an open road.

Choose the Bridgestone S 21 R for unmatched traction, rapid response, and lasting performance that keeps your motorcycle at the forefront of speed and safety.