CST Scout Tire – 20x4.0, E-Bike Rated, Wire Bead, Puncture Protection
The CST Scout 20x4.0 is a high-volume fat tire originally designed for e-moped use, now widely used on fat tire e-bikes. It combines a stable, fast-rolling center profile with large siped tread blocks for grip, making it a solid option for pavement, hardpack, and mixed-use riding.
Key Functional Details
- 20x4.0 fat tire designed for e-bike and e-moped applications
- Offset square tread blocks with siping for improved grip
- Wide channels between knobs for traction and debris clearing
- Rounded profile for reduced rolling resistance on pavement
- Integrated puncture protection layer with reinforced casing fibers
- E25 rating for e-bikes up to 25 km/h (15 mph)
- Durable wire bead construction
- 60 TPI casing for balance of durability and ride quality
Technical Specifications
| Brand | CST (CST Premium) |
| Model | Scout |
| Size | 20 x 4.0 |
| ISO | 406 |
| Bead | Wire |
| TPI | 60 |
| Max PSI | 30 PSI |
| Weight | 1674g |
| Puncture Protection | Reinforced casing fibers (belted) |
| E-Bike Rating | E25 (up to 25 km/h / 15 mph) |
| Sidewall | Black (non-reflective) |
| UPC | 6933882532885 |
Compatibility & Technical Notes
Good Fit:
- 20" fat tire e-bikes (common on folding and utility models)
- E-bikes using 20x4.0 (406) tire sizing
- Riders primarily on pavement, hardpack, or light gravel
- Replacement tire for many fat tire commuter e-bikes
Not A Fit:
- 26" or 27.5" fat bikes (size mismatch)
- Rims not designed for 4.0" width tires
- High-speed Class 3 e-bikes exceeding E25 rating
- Loose sand or aggressive off-road conditions (limited deep traction)
Always confirm tire size printed on the sidewall of your existing tire before ordering (20x4.0 / ISO 406).
Service / Ownership Context
Best run between 15–30 PSI depending on rider weight and terrain. Lower pressure improves comfort and grip, while higher pressure increases efficiency on pavement. Heavier casing provides durability but adds rotational weight.
Fit & Use Signals
- Ideal for fat tire e-bike commuters
- Good for riders prioritizing durability and puncture resistance
- Balanced option for mixed pavement and light trail use
- Common OEM replacement tire for 20x4.0 e-bikes
This is a go-to replacement tire for 20x4.0 e-bikes, especially budget and mid-range models like Himiway-style setups. Customers often confuse ISO sizing—406 is correct for 20” fat tires, not 451 or standard BMX 20”. Wire bead means it won’t fold—make sure customers know for transport/storage. Not great in sand or snow compared to more aggressive tread patterns. Upsell opportunity: heavy-duty tubes or tire liners since these bikes are heavy and prone to flats. Also check rim width—too narrow and this tire will feel unstable.