33 inch tire equals what metric size? There’s no single answer, because a 33-inch tire is defined by its overall height, while metric sizes describe width, sidewall ratio, and rim size. The closest metric equivalents depend on your wheel diameter: on a 17-inch rim, a 285/70R17 comes out to about 32.7 inches tall, while on a 20-inch rim, a 275/60R20 lands right at about 33 inches. The chart below covers the common options.
33 Inch Tire Metric Conversion Chart
| Rim Size | Metric Size | Approx. Diameter |
|---|---|---|
| 16 inch | 285/75R16 | 32.8 in |
| 17 inch | 285/70R17 | 32.7 in |
| 17 inch | 295/70R17 | 33.3 in |
| 18 inch | 295/65R18 | 33.1 in |
| 18 inch | 275/70R18 | 33.2 in |
| 20 inch | 275/60R20 | 33.0 in |
| 20 inch | 305/55R20 | 33.2 in |
These figures are calculated from the size codes, so actual measured height varies slightly between tire brands and tread designs. Check the manufacturer’s spec sheet for the exact diameter of the tire you’re buying.
How to Convert Metric Tire Sizes to Inches
A metric size like 285/70R17 has three key numbers. The 285 is the tread width in millimeters. The 70 is the aspect ratio, meaning the sidewall height is 70% of the width. The 17 is the wheel diameter in inches. To get overall diameter:
- Multiply the width by the aspect ratio: 285 × 0.70 = 199.5 mm of sidewall.
- Convert to inches by dividing by 25.4: 199.5 ÷ 25.4 = 7.85 inches.
- Double it, since there’s sidewall above and below the wheel: 7.85 × 2 = 15.71 inches.
- Add the rim diameter: 15.71 + 17 = 32.71 inches.
Flotation Sizes vs. Metric Sizes
Many off-road tires are labeled in flotation sizing, such as 33×12.50R17. Here, 33 is the overall height, 12.50 is the width in inches, and 17 is the rim size. A 12.50-inch width is about 318 mm, so a 33×12.50R17 is noticeably wider than a 285/70R17, even though both are close to 33 inches tall. If you’re matching tires for fitment, compare both height and width, not just the “33.”
Before You Switch to 33-Inch Tires
Going up to 33s is a popular upgrade for trucks and off-roaders like the Jeep Wrangler, but bigger tires affect more than looks. They can rub on fenders or suspension parts without a lift or level kit, and they throw off your speedometer if they’re taller than stock. They also change your effective gearing, which matters if you tow. If you haul heavy loads, check your truck’s capacity first, starting with whether your F150 has the Max Tow Package.
Larger, heavier tires also wear differently. Keeping them properly aligned and rotated helps avoid uneven wear like tire feathering, and our guide on how often to rotate tires covers the basics. After installing new tires, confirm your tire pressure sensors read correctly, since a bad tire sensor can trigger false warnings.
Conclusion
So, a 33 inch tire equals what metric size? It depends on the rim: 285/75R16 on 16-inch wheels, 285/70R17 or 295/70R17 on 17s, 295/65R18 or 275/70R18 on 18s, and 275/60R20 or 305/55R20 on 20s. Use the formula above to check any size, and confirm the real diameter on the tire maker’s spec sheet before you buy.
Frequently Asked Questions
Is a 285/70R17 a true 33-inch tire?
Not quite. A 285/70R17 calculates to about 32.7 inches, which is why it’s often called a 33-inch equivalent. Actual height varies a little by brand and tread design.
What size is 33×12.50R17 in metric?
There’s no exact match, but it’s about 33 inches tall and roughly 318 mm wide. A 315/70R17 is about 34.4 inches tall, and a 295/70R17 is about 33.3 inches, so most people pick the closest height or width depending on fitment.
Do I need a lift kit for 33-inch tires?
It depends on the vehicle. Some trucks and Jeeps fit 33s stock or with a leveling kit, while others need a lift or trimming to avoid rubbing at full steering lock or under suspension compression.
Will 33-inch tires affect my speedometer?
Yes, if they’re taller than your stock tires. A taller tire covers more ground per revolution, so your speedometer will read lower than your actual speed unless it’s recalibrated.
