Selecting Rear Tire Sizes for Case 580 CK Backhoe

[MikePhua]

When you're restoring or maintaining a vintage Case 580 CK Construction-King backhoe, choosing the right rear tire size can be surprisingly complex. Factory literature and real-world use sometimes diverge, leading to a mix of options, each affecting clearance, load capability, and performance. Here's a user-friendly breakdown, enriched with historical context and practical guidance.
Historical Context and Equipment Background
J.I. Case launched the 580 CK Series in the late 1960s as a tough industrial tractor that could be fitted with a backhoe—a logical extension of their earlier loader designs. The “CK” stands for Construction King, reflecting its rugged construction and versatility. Estimates suggest thousands of units rolled off the line between 1966 and 1971, mostly in industrial rather than agricultural spec, so tire selection often leaned heavyduty.
Factory-Specified Tire Sizes
Original industrial factory specs indicate the following baseline configuration:

• Front industrial tires: 7.50 × 16
  
• Rear industrial tires: 14.9 × 24
  

These reflect the standard, well-proven setup designed for balanced ride height, stability under load, and compatibility with standard axle/rim dimensions.
Alternate Sizes and Their Impact
Some service manuals and parts catalogs also mention that some versions used:

• 16.9 × 24 when fitted with the backhoe
  
• 17.5 × 24 especially when a forklift attachment was added
  

In practice, enthusiasts and restorers report that both the standard 14.9 × 24 and larger 16.9 × 24 have been used successfully. The larger sizes can raise clearance by several inches, offering better ground clearance and reach—but may run into clearance challenges with outriggers or loader frames.
One experienced owner described that while 16.9 × 24 tires may fit, their ridges make first-gear low-range less usable, and the proximity to outrigger arms may be problematic. Another noted the importance of rim design—the “dish” (offset) must accommodate the loader frame.
Technical Considerations and Recommendations

• Clearance Concerns: If the tires begin to brush the outriggers when deployed, the larger sizes may not be practical. Inspect clearance when fully extended.
  
• Rim Compatibility: The original industrial rear rims were about 13 inches wide. Larger tire sizes like 16.9 × 24 often require 15-inch‐wide rims with an appropriate dish.
  
• Load Rating (Ply Rating): Original front tires likely had an 8-ply rating. A 10-ply upgrade is recommended for durability.
  
• Ride Height: Owners pursuing more ground clearance often opt for the 16.9 × 24, especially for rough terrain or farm use.
  

Practical Advice

• If you're restoring to factory condition, 14.9 × 24 industrial tires on original rims are the safe bet.
  
• If you need extra clearance and are willing to adjust or upgrade rims, 16.9 × 24 can be a good choice—just test fit and confirm outrigger clearance.
  
• Avoid mixing agricultural (AG) tread styles unless you're certain of fit and application—industrial tread offers better ply strength and durability for a heavy backhoe.
  
• When replacing tires, consider also refurbishing or repainting rims, and get a solid mobile tire service if you're in a rural area—many providers can handle large OTR tires onsite.
  

Checklist

• List of popular rear tire options:
  • 14.9 × 24 – standard industrial
    
  • 16.9 × 24 – slightly larger, better clearance
    
  • 17.5 × 24 – less common, special use with forklift or tall loader
    
• Checklist when choosing:
  • Measure clearance around outriggers and loader frame
    
  • Confirm rim width and dish compatibility
    
  • Assess ply rating for weight and terrain
    
  • Consider mobility and service availability in your area
    

Mini Anecdote
On a small Vermont farm, a 1970 580 CK sat with 40-year-old rear tires, sagging so low that even light mud on the paddles created blockage. Switching to 16.9 × 24 lifted the entire machine nearly two inches—and during the first snow, the added ground clearance kept the pump house driveway clear when smaller tires would have bogged down. The bigger tires fit just right—cleared the loader frame—and gained vital clearance without sacrificing driveability.
Summary
For a vintage Case 580 CK backhoe, the choice boils down to a balance between originality and practicality. The 14.9 × 24 industrial tire on original rims stays true to specs. But if you need more ride height, the 16.9 × 24 is a smart upgrade—just verify clearances and rim fit. Always pair with at least a 10-ply front tire to endure modern workloads and rough terrain.