You're staring at the sidewall of your forklift tire and seeing something like "18x7x12-1/8" or "6.50-10NHS." What does any of this mean? And more importantly, how do you use these numbers to order the right replacement?
Forklift tire sizing looks confusing at first, but once you understand the system, you'll be able to decode any tire size in seconds. Let's break it down.
The Two Main Sizing Systems
Forklift tires use two different numbering systems depending on the tire type:
- Industrial/Press-On Format: Used for cushion tires and press-on solid tires (e.g., 18x7x12-1/8)
- Standard Tire Format: Used for pneumatic and solid pneumatic tires (e.g., 6.50-10NHS)
Let's decode each one.
Reading Industrial/Press-On Tire Sizes
Press-on tires and cushion tires typically use a three-number format with an optional fraction:
Example: 18 x 7 x 12-1/8
| Number | What It Means | In This Example |
|---|---|---|
| First Number (18) | Overall diameter in inches | 18 inches tall |
| Second Number (7) | Tire width in inches | 7 inches wide |
| Third Number (12-1/8) | Inner diameter (rim/band size) | 12-1/8 inch bore |
The fraction matters. That 1/8" in "12-1/8" is critical. A tire sized 18x7x12 won't fit on equipment designed for 18x7x12-1/8. Always match the exact size, including fractions.
Step 1: Measure the Overall Diameter
This is the total height of the tire when new. Place a straightedge across the tire and measure from floor to top. New tires should match or be slightly larger than this measurement (worn tires will be smaller).
Step 2: Measure the Width
Measure across the widest point of the tread face. This is typically the second number in the size designation.
Step 3: Measure the Inner Diameter
This is the bore that fits onto the rim or band. For press-on tires, this is the diameter of the steel band the tire mounts to. Measure the inside opening—this is your third number.
Reading Pneumatic Tire Sizes
Pneumatic and solid pneumatic tires use a different format that looks like this:
Example: 6.50-10NHS or 28x9-15
Format 1: Width-Rim Diameter (e.g., 6.50-10NHS)
| Component | What It Means | In This Example |
|---|---|---|
| 6.50 | Tire width in inches | 6.5 inches wide |
| 10 | Rim diameter in inches | Fits 10-inch rim |
| NHS | Not for Highway Service | Industrial use only |
Format 2: OD x Width-Rim (e.g., 28x9-15)
| Component | What It Means | In This Example |
|---|---|---|
| 28 | Overall diameter in inches | 28 inches tall |
| 9 | Tire width in inches | 9 inches wide |
| 15 | Rim diameter in inches | Fits 15-inch rim |
Additional Markings to Look For
Beyond the size numbers, tire sidewalls contain other important information:
- Ply Rating: Indicates load capacity (higher ply = higher capacity)
- Load Capacity: Maximum weight the tire can support (in lbs or kg)
- Compound Type: Some tires indicate rubber compound (e.g., "NM" for non-marking)
- Manufacturer: Brand name and sometimes model designation
- DOT Code: For pneumatic tires, indicates manufacturing date
Where to Find Size Information
If the sidewall markings are worn or unreadable, you have options:
- Equipment Manual: Lists original tire specifications
- Nameplate: Usually on the forklift frame, shows tire size requirements
- Measure Directly: Use the measurements described above
- Cross-Reference: Use the forklift model number to look up tire specs
Common Mistakes to Avoid
Don't estimate. Tire sizes that look similar (18x7x12 vs 18x7x12-1/8) are not interchangeable. The wrong size creates safety hazards and can damage your equipment.
Check all positions. Forklifts often use different tire sizes for drive wheels vs steer wheels. Don't assume all four corners are the same.
Account for wear. If you're measuring a worn tire, the overall diameter will be smaller than the original specification. When in doubt, go by the sidewall markings rather than measurements.
Need Help Finding Your Size?
Not sure what size you need? Submit a parts inquiry with your forklift make, model, and serial number, and we'll identify the correct tires for your equipment. Or call us at (562) 693-7748—we've been matching tires to forklifts for decades.
Ready to order? Browse our complete tire inventory including press-on, pneumatic, and solid options for all major forklift brands.