Product Description
Smooth Crown Poly Drive Tire
Specifications: 21.000 inch diameter x 7.000 inch width (21.000" x 7.000" | 21 x 7 wheel | 21 x 7-0 | 533.40mm x 177.80mm)
Specifications
Wheel Specifications
| Outside Diameter (in) | 21.000 |
| Width (in) | 7.000 |
| Outside Diameter (mm) | 533.40 |
| Width (mm) | 177.80 |
| Material | Polyurethane |
Frequently Asked Questions
Q: What does SC stand for on SU 21X7X15-SC-P and how does smooth crown differ from smooth flat?
A: SC stands for Smooth Crown. Crown profile tires have a slight convex curve across the tread surface (higher in the center, lower at edges), while smooth flat tires are completely flat. SU 21X7X15-SC-P has a smooth crown polyurethane tire that provides better steering control and self-centering on the hub compared to flat tires. Crown profile is preferred for high-speed maneuvers and indoor jacks where precise steering is required. The 21x7 size and 15mm bore fit standard lift truck axles rated for 21 inch wheels.
Q: Should I use SU 21X7X15-SC-P (crown) or SU 21 X 7 X 15-SF-R (flat rubber) for my application?
A: Choose smooth crown polyurethane (SC-P) for smooth indoor floors, high-speed operation, and applications requiring precise steering. Choose smooth flat rubber (SF-R) for outdoor use, wet surfaces, and environments where traction matters more than steering precision. SC-P tires are harder and more durable indoors; SF-R rubber tires grip better outdoors. Crown profile reduces edge wear on flat tires, extending lifespan on smooth concrete. If your jack operates on a mix of surfaces, smooth crown polyurethane is the better compromise.
Q: What is the load capacity and expected lifespan of SU 21X7X15-SC-P polyurethane tire?
A: SU 21X7X15-SC-P supports up to 2000 lbs per wheel with a typical lifespan of 2-4 years or 4000-6000 operating hours. Polyurethane compound resists abrasion, oil, and chemicals better than rubber, making it ideal for warehouses, manufacturing plants, and indoor facilities. Crown profile distributes contact pressure more evenly, reducing flat spotting and extending tire life by 10-20 percent compared to smooth flat tires. Rotation between left and right wheels every 12 months further extends lifespan.
Q: Does SU 21X7X15-SC-P crown profile require different installation than flat tires?
A: Installation method is the same: use a tire press set to 8-12 tons for a 21 inch press-on tire. Crown profile tires are slightly stiffer than flat tires and may require slightly higher press force (1-2 tons additional). Do not use a hammer-on method for press-on tires. Ensure the core hub bore matches 15mm before pressing. After installation, verify the crown is centered (higher point aligned with the axle center) and the tire is not tilted. A misaligned crown profile will cause steering vagueness and uneven wear.
Q: How do polyurethane crown tires perform on wet floors or outdoor conditions?
A: SU 21X7X15-SC-P smooth crown polyurethane does not perform well on wet or outdoor surfaces. Polyurethane has lower friction than rubber in wet conditions and the smooth profile provides minimal tread grip. If your jack is used outdoors or on wet warehouse floors, do not use this tire. Instead, select SU 21 X 7 X 15-SF-R (smooth flat rubber) or consider a traction profile polyurethane tire if available. Store polyurethane tires indoors; UV exposure and temperature extremes degrade the compound and reduce lifespan.
Q: Is SU 21X7X15-SC-P equivalent to any competitor crown profile polyurethane tires?
A: SU 21X7X15-SC-P is equivalent to Crown WH-TR21070000SC, Yale YL-580072005CP, and Hyster 1302305 when all use the same 21x7 smooth crown polyurethane profile with 15mm bore. Always verify the profile (crown vs flat) and material (poly vs rubber) in the catalog; a flat polyurethane tire and a crown polyurethane tire are not interchangeable despite similar part numbers. Cross-referencing is safe if all specs match exactly: OD, width, bore, profile, and material.