ULTIMA 37-608 Kool Kat Rear Wheel Rigid 5.5

( Brand: Ultima ), ( Manufacturer Part Number: 37-608 ), ( Machine Type: Street Motorcycle ), ( Compatible Fastener Seat Type: Axle ), ( Wheel Material: Aluminum ), ( Placement On Vehicle: Rear Wheel ), ( Type: Rim ), ( Backspacing: 5.5 In ), ( Manufacturer Warranty: 1 Year ), ( Wheel Width: 5.5 ), ( Finish: Polished )

Review ULTIMA Kool Kat Rear Wheel 5.5 Harley Custom Rigid fits SOFTAIL CHOPPER BOBBER 2018

The **Ultima 37-608 Kool Kat Rear Wheel** is a meticulously engineered, high-performance aftermarket wheel designed specifically for Harley-Davidson Softail, Rigid, Chopper, and Bobber models equipped with 18-inch wheels and a 5.5-inch tire width. Crafted from premium-grade aluminum alloy, this wheel combines cutting-edge aerodynamics with rugged durability, ensuring both style and substance for riders seeking a bold, aggressive stance. The **Kool Kat** series is renowned for its distinctive, angular design, which not only enhances the bike s visual appeal but also optimizes airflow for improved cooling and reduced drag, contributing to better overall performance. The wheel s deep-dish construction provides a wide, aggressive stance, perfect for chopper and bobber builds where a low, wide profile is desired. The **5.5-inch tire clearance** ensures compatibility with a wide range of aftermarket tires, from sporty street tires to rugged off-road options, making it a versatile choice for custom builds. Engineered with precision, the wheel features a **5-spoke design** that balances strength and weight, reducing unsprung mass while maintaining structural integrity. The **Kool Kat** is not just an aesthetic upgrade but a functional one, designed to complement the aggressive, low-slung aesthetics of a chopper or bobber while delivering the performance expected from a high-quality aftermarket component. Whether you're building a classic-style bobber or a modern chopper, this wheel adds a touch of boldness and character, ensuring your Harley stands out on the road with confidence and style.

### **Pros and Cons of buying a Ultima 37-608 Kool Kat Rear Wheel (18" x 5.5") for a Harley Softail Rigid, Chopper, or Bobber**

1. **Improved Ride Comfort and Stability**

The Kool Kat rear wheel is designed with a wider, more stable platform than stock Harley wheels. This reduces wobble and vibration, especially at higher speeds, which is particularly beneficial for choppers and bobbers that often have longer wheelbases and lighter frames. The wider footprint also helps distribute weight better, improving traction on rough surfaces.

2. **Better Weight Distribution**

Choppers and bobbers often have extended forks, longer rear ends, or modified suspensions, which can shift weight unevenly. The Kool Kat s reinforced construction and balanced design help counteract this, making the bike feel more planted and predictable.

3. **Durability and Reinforced Construction**

Ultima wheels are known for their high-quality materials and robust build. The Kool Kat features a **dual-pin axle** and **reinforced spokes**, reducing the risk of wheel wobble or spoke failure common issues with aftermarket wheels on modified Harleys. This is especially useful for riders who push their bikes hard or ride in aggressive conditions.

4. **Compatibility with Aftermarket Modifications**

Many choppers and bobbers feature custom suspensions, lowered frames, or extended forks, which can stress stock wheels. The Kool Kat is designed to handle these modifications better than OEM wheels, reducing the likelihood of premature wear or failure.

5. **Reduced Vibration and Fatigue**

The wider rim and reinforced hub help dampen road vibrations, which is crucial for long rides. Stock Harley wheels on modified bikes can transmit more vibration to the rider, leading to discomfort over time. The Kool Kat mitigates this issue.

6. **Aesthetic Appeal**

The Kool Kat has a sleek, modern look that complements the aggressive styling of choppers and bobbers. It s a subtle upgrade that enhances the bike s appearance without being overly flashy.

7. **Compatibility with Wide or Custom Tires**

The 18" x 5.5" size allows for wider tire options, which can improve grip and comfort. Many chopper and bobber riders opt for wider rear tires for better stability, and the Kool Kat accommodates this well.

8. **Easier Maintenance and Adjustability**

Ultima wheels are known for their ease of maintenance. The dual-pin axle system allows for quick adjustments, and the spokes are less prone to stretching over time compared to some budget wheels.

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1. **Higher Upfront Cost**

The Kool Kat is a premium wheel, and its price point is significantly higher than stock Harley wheels or basic aftermarket options. For riders on a tight budget, this may be a major drawback, especially if the bike is already heavily modified.

2. **Potential Weight Increase**

While the Kool Kat is more durable, it is heavier than stock Harley wheels. This added weight can slightly reduce acceleration, though the difference is usually negligible unless the bike is heavily modified with lightweight components elsewhere.

3. **Installation Complexity**

Swapping a rear wheel on a Harley especially a modified one can be tricky. Some riders may need to adjust the chain tension, sprocket alignment, or suspension settings after installation. If not done correctly, it could lead to chain slippage or handling issues.

4. **Limited Availability and Lead Times**

Ultima wheels can sometimes have longer lead times due to demand or manufacturing schedules. This may delay a rider s plans if they re in a hurry to complete modifications.

5. **Potential for Overkill on Stock or Lightly Modified Bikes**

If the Harley is a stock Softail or only has minor modifications, the Kool Kat may offer little practical benefit beyond aesthetics. For such bikes, a stock wheel or a mid-range aftermarket option might suffice.

6. **Compatibility with Certain Modifications**

Some extreme chopper or bobber builds (e.g., those with drastically lowered frames or custom suspensions) may require additional adjustments to ensure the Kool Kat wheel aligns properly with the swingarm and drive train. A professional wheel alignment check may be necessary.

7. **Tire Clearance Concerns**

While the 18" x 5.5" size is versatile, riders considering extremely wide tires (e.g., 210 mm) may need to verify clearance with fenders, brakes, or other components. Some aftermarket fenders or brake systems may require modifications to accommodate wider setups.

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### **Conclusion and Recommendation**

The **Ultima 37-608 Kool Kat rear wheel (18" x 5.5")** is an excellent choice for riders on **Harley-Davidson Softail Rigids, choppers, or bobbers** that have been modified with extended forks, lowered frames, or custom suspensions. Its **reinforced construction, improved stability, and reduced vibration** make it a worthwhile investment for those who prioritize durability and ride quality over cost.

**For whom is it ideal?**

- Riders who have **heavily modified** their Harley with aggressive geometry changes.

- Those who experience **excessive wobble, vibration, or instability** with stock wheels.

- Enthusiasts who want a **premium, long-lasting wheel** that can handle high-speed riding and rough conditions.

- Owners of **choppers or bobbers** where weight distribution and handling are critical.

**For whom might it be unnecessary?**

- Riders with **stock or lightly modified** Softails who don t experience wheel-related issues.

- Those on a **tight budget** who can achieve similar benefits with a lower-cost aftermarket wheel.

- Owners of **extremely minimalist builds** where weight savings are a priority.

If you ve invested in **significant modifications** to your Harley and notice **vibration, wobble, or poor handling**, the Kool Kat is a **strong upgrade** that will enhance both performance and comfort. However, if your bike remains mostly stock or you re looking for a budget-friendly solution, consider alternatives like **OEM wheels with reinforced spokes** or **mid-range aftermarket options** (e.g., from brands like **Dunlop, Shinko, or IZIP**).

For most **choppers and bobbers**, the Kool Kat is a **smart, long-term investment** that pays off in reliability and ride quality. Just ensure proper installation and alignment to maximize its benefits.

Details:

Came off a 1990 flatcar no damage.

part #: 37608 price

• $483.99

specifications cywhemo:

• for models: Chopper, Bobber, Softail
• for makes: Harley
• for years: 2018
• brand: Ultima
• mpn: 37-608
• machine type: Street Motorcycle
• compatible fastener seat type: Axle
• wheel material: Aluminum
• placement on vehicle: Rear Wheel
• type: Rim
• backspacing: 5.5 In
• manufacturer warranty: 1 Year
• wheel width: 5.5
• finish: Polished

seller cywhemo:

• city: Toledo, Ohio
• rating: 0.0%
• # reviews: 1

returns cywhemo:

• policy: No Returns

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• credit card: Discover

offer cywhemo:

• sold: 0
• started: March 13, 2026
• quantity: 1
• availability: In Stock
• best offers: True
• options: Ship-to-home

general cywhemo:

• Motorcycle Scooter Parts Accessories > Wheels, Tires Parts > Wheels Rims
• condition: Used

shipping cywhemo:

• type: Calculated
• class: Standard
• carrier: USPS
• service: USPS Ground Advantage
• cost: $75.89
• transit: 5-12 Days

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