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285/30R21 Tire Size
All You Need to Know About 285/30R21 Tires
285/30R21 tires have a section width of 285 millimeters (mm), an aspect ratio of 30%, radial construction, and a 21-inch wheel diameter. Before buying tires sized 285/30R21, converting 285/30R21 measurements into inches, comparing them with similar tire sizes such as 265/30R21 and 285/30R20, and understanding interchangeability limits helps drivers confirm correct fitment and avoid clearance or calibration issues.
What Are the Dimensions of a 285/30R21 Tire in Inches?
A 285/30R21 tire has a section width of 11.22 inches (≈ 11.2") and a sidewall height of 3.37 inches (≈ 3.4"). The overall diameter of a 285/30R21 tire is 27.73 inches (≈ 27.7"), and the circumference is approximately 87.10 inches (≈ 87.1"). The recommended rim width range for the 285/30R21 size is 9.5 to 11.0 inches.
In inches, the 285/30R21 tire size can be represented as 27.7" × 11.2" R21.
How tall and wide are 285/30R21 tires?
A 285/30R21 tire is approximately 27.73 inches (704.4 mm) tall and 11.22 inches (285 mm) wide.
Comparison of 285/30R21 With Similar Tire Sizes
Comparing 285/30R21 with 265/30R21 and 285/30R20 highlights how changes in width and wheel diameter affect stance, ride characteristics, and interchangeability.
What Is the Difference Between 285/30R21 vs 265/30R21?
The main difference between 285/30R21 and 265/30R21 is the section width. Both tires share the same aspect ratio and rim diameter, but the wider tire also has a slightly taller overall diameter. The 285/30R21 has a sidewall height of 85.50 mm (≈ 3.37") and an overall diameter of 704.40 mm (≈ 27.73"). The 265/30R21 has a sidewall height of 79.50 mm (≈ 3.13") and an overall diameter of 692.40 mm (≈ 27.27").
This means the 285/30R21 is 20 mm wider, has a 6.00 mm (≈ 0.24") taller sidewall, and is 12.00 mm (≈ 0.47") larger overall.
285/30R21 vs 265/30R21 Tire Size Comparison Table
Tire Dimension | 285/30R21 (mm & in) | 265/30R21 (mm & in) | Difference (mm & in) | Percentage Difference |
Section Width | 285 mm (≈ 11.22") | 265 mm (≈ 10.43") | 20 mm (≈ 0.79") | ≈ 7.5% |
Sidewall Height | 85.50 mm (≈ 3.37") | 79.50 mm (≈ 3.13") | 6.00 mm (≈ 0.24") | ≈ 7.5% |
Overall Diameter | 704.40 mm (≈ 27.73") | 692.40 mm (≈ 27.27") | 12.00 mm (≈ 0.47") | ≈ 1.73% |
Circumference | 2212.9 mm (≈ 87.10") | 2175.2 mm (≈ 85.65") | 37.7 mm (≈ 1.48") | ≈ 1.73% |
Radius | 352.20 mm (≈ 13.87") | 346.20 mm (≈ 13.63") | 6.00 mm (≈ 0.24") | ≈ 1.73% |
Rim Diameter | 21" | 21" | — | — |
Recommended Rim Width | 9.5–11.0" | 9.0–10.0" | — | — |
Can I use 265/30R21 instead of 285/30R21?
Yes, this is generally an acceptable and well-within-tolerance alternative. The overall diameter difference is under 2%, so speedometer accuracy and vehicle calibration remain very close to stock. The narrower width may slightly reduce grip and steering weight, but for most vehicles, this swap works without major drawbacks as long as wheel width and clearance are appropriate.
While the dimensions are fine, there are two practical factors to check:
- Load Index: 285/30R21 tires typically have a load index of 100 (1,764 lbs), while 265/30R21 tires often have a lower index of 96 (1,565 lbs). You must ensure the 265 tire still meets the minimum load requirement listed on your vehicle's door placard.
- Rim Width: A 265/30R21 tire is ideally mounted on a 9.0" to 10.0" rim. If your current 285 wheels were designed for 285s and are 10.5'' or 11.0" wide, the 265 tire will look significantly "stretched," which can expose the rim lip to curb damage.
Recommended 265/30R21 Tires
If you plan to switch to 265/30R21 instead of 285/30R21, well-regarded options in this size include:
What Is the Difference Between 285/30R21 vs 285/30R20?
The main difference between 285/30R21 and 285/30R20 is the rim diameter. Both tires share the same width and aspect ratio, but the smaller wheel results in a shorter overall diameter. The 285/30R21 has an overall diameter of 704.40 mm (≈ 27.73"). The 285/30R20 has a sidewall height of 85.50 mm (≈ 3.37") and an overall diameter of 678.60 mm (≈ 26.72").
This means the 285/30R20 is 25.80 mm (≈ 1.02") smaller overall, even though the sidewall height remains the same.
285/30R21 vs 285/30R20 Tire Size Comparison Table
Tire Dimension | 285/30R21 (mm & in) | 285/30R20 (mm & in) | Difference (mm & in) | Percentage Difference |
Section Width | 285 mm (≈ 11.22") | 285 mm (≈ 11.22") | 0 | 0% |
Sidewall Height | 85.50 mm (≈ 3.37") | 85.50 mm (≈ 3.37") | 0 | 0% |
Overall Diameter | 704.40 mm (≈ 27.73") | 679.00 mm (≈ 26.73") | 25.40 mm (≈ 1.00") | ≈ 3.61% |
Circumference | 2212.9 mm (≈ 87.10") | 2132.9 mm (≈ 84.00") | 80.0 mm (≈ 3.15") | ≈ 3.61% |
Radius | 352.20 mm (≈ 13.87") | 339.50 mm (≈ 13.37") | 12.70 mm (≈ 0.50") | ≈ 3.61% |
Rim Diameter | 21" | 20" | — | — |
Recommended Rim Width | 9.5–11.0" | 9.5–11.0" | — | — |
Can I use 285/30R20 instead of 285/30R21?
No, a 285/30R20 tire cannot be mounted on a 21-inch rim. First of all, switching to this size requires purchasing 20-inch wheels, which is a mandatory change. Even after changing wheels, the overall diameter reduction of ≈ 3.7% places this swap in the borderline range, which may affect speedometer accuracy, ride height, and vehicle calibration. Your vehicle would sit 0.5 inches lower to the ground. For a performance car that is likely already low, this increases the risk of scraping the undercarriage or front splitter. The rim mismatch is a "hard no," and even with the correct wheels, the diameter drop is significant enough to cause calibration concerns.
All You Need to Know About 285/30R21 Tires
285/30R21 tires have a section width of 285 millimeters (mm), an aspect ratio of 30%, radial construction, and a 21-inch wheel diameter. Before buying tires sized 285/30R21, converting 285/30R21 measurements into inches, comparing them with similar tire sizes such as 265/30R21 and 285/30R20, and understanding interchangeability limits helps drivers confirm correct fitment and avoid clearance or calibration issues.
What Are the Dimensions of a 285/30R21 Tire in Inches?
A 285/30R21 tire has a section width of 11.22 inches (≈ 11.2") and a sidewall height of 3.37 inches (≈ 3.4"). The overall diameter of a 285/30R21 tire is 27.73 inches (≈ 27.7"), and the circumference is approximately 87.10 inches (≈ 87.1"). The recommended rim width range for the 285/30R21 size is 9.5 to 11.0 inches.
In inches, the 285/30R21 tire size can be represented as 27.7" × 11.2" R21.
How tall and wide are 285/30R21 tires?
A 285/30R21 tire is approximately 27.73 inches (704.4 mm) tall and 11.22 inches (285 mm) wide.
Comparison of 285/30R21 With Similar Tire Sizes
Comparing 285/30R21 with 265/30R21 and 285/30R20 highlights how changes in width and wheel diameter affect stance, ride characteristics, and interchangeability.
What Is the Difference Between 285/30R21 vs 265/30R21?
The main difference between 285/30R21 and 265/30R21 is the section width. Both tires share the same aspect ratio and rim diameter, but the wider tire also has a slightly taller overall diameter. The 285/30R21 has a sidewall height of 85.50 mm (≈ 3.37") and an overall diameter of 704.40 mm (≈ 27.73"). The 265/30R21 has a sidewall height of 79.50 mm (≈ 3.13") and an overall diameter of 692.40 mm (≈ 27.27").
This means the 285/30R21 is 20 mm wider, has a 6.00 mm (≈ 0.24") taller sidewall, and is 12.00 mm (≈ 0.47") larger overall.
285/30R21 vs 265/30R21 Tire Size Comparison Table
Tire Dimension | 285/30R21 (mm & in) | 265/30R21 (mm & in) | Difference (mm & in) | Percentage Difference |
Section Width | 285 mm (≈ 11.22") | 265 mm (≈ 10.43") | 20 mm (≈ 0.79") | ≈ 7.5% |
Sidewall Height | 85.50 mm (≈ 3.37") | 79.50 mm (≈ 3.13") | 6.00 mm (≈ 0.24") | ≈ 7.5% |
Overall Diameter | 704.40 mm (≈ 27.73") | 692.40 mm (≈ 27.27") | 12.00 mm (≈ 0.47") | ≈ 1.73% |
Circumference | 2212.9 mm (≈ 87.10") | 2175.2 mm (≈ 85.65") | 37.7 mm (≈ 1.48") | ≈ 1.73% |
Radius | 352.20 mm (≈ 13.87") | 346.20 mm (≈ 13.63") | 6.00 mm (≈ 0.24") | ≈ 1.73% |
Rim Diameter | 21" | 21" | — | — |
Recommended Rim Width | 9.5–11.0" | 9.0–10.0" | — | — |
Can I use 265/30R21 instead of 285/30R21?
Yes, this is generally an acceptable and well-within-tolerance alternative. The overall diameter difference is under 2%, so speedometer accuracy and vehicle calibration remain very close to stock. The narrower width may slightly reduce grip and steering weight, but for most vehicles, this swap works without major drawbacks as long as wheel width and clearance are appropriate.
While the dimensions are fine, there are two practical factors to check:
- Load Index: 285/30R21 tires typically have a load index of 100 (1,764 lbs), while 265/30R21 tires often have a lower index of 96 (1,565 lbs). You must ensure the 265 tire still meets the minimum load requirement listed on your vehicle's door placard.
- Rim Width: A 265/30R21 tire is ideally mounted on a 9.0" to 10.0" rim. If your current 285 wheels were designed for 285s and are 10.5'' or 11.0" wide, the 265 tire will look significantly "stretched," which can expose the rim lip to curb damage.
Recommended 265/30R21 Tires
If you plan to switch to 265/30R21 instead of 285/30R21, well-regarded options in this size include:
What Is the Difference Between 285/30R21 vs 285/30R20?
The main difference between 285/30R21 and 285/30R20 is the rim diameter. Both tires share the same width and aspect ratio, but the smaller wheel results in a shorter overall diameter. The 285/30R21 has an overall diameter of 704.40 mm (≈ 27.73"). The 285/30R20 has a sidewall height of 85.50 mm (≈ 3.37") and an overall diameter of 678.60 mm (≈ 26.72").
This means the 285/30R20 is 25.80 mm (≈ 1.02") smaller overall, even though the sidewall height remains the same.
285/30R21 vs 285/30R20 Tire Size Comparison Table
Tire Dimension | 285/30R21 (mm & in) | 285/30R20 (mm & in) | Difference (mm & in) | Percentage Difference |
Section Width | 285 mm (≈ 11.22") | 285 mm (≈ 11.22") | 0 | 0% |
Sidewall Height | 85.50 mm (≈ 3.37") | 85.50 mm (≈ 3.37") | 0 | 0% |
Overall Diameter | 704.40 mm (≈ 27.73") | 679.00 mm (≈ 26.73") | 25.40 mm (≈ 1.00") | ≈ 3.61% |
Circumference | 2212.9 mm (≈ 87.10") | 2132.9 mm (≈ 84.00") | 80.0 mm (≈ 3.15") | ≈ 3.61% |
Radius | 352.20 mm (≈ 13.87") | 339.50 mm (≈ 13.37") | 12.70 mm (≈ 0.50") | ≈ 3.61% |
Rim Diameter | 21" | 20" | — | — |
Recommended Rim Width | 9.5–11.0" | 9.5–11.0" | — | — |
Can I use 285/30R20 instead of 285/30R21?
No, a 285/30R20 tire cannot be mounted on a 21-inch rim. First of all, switching to this size requires purchasing 20-inch wheels, which is a mandatory change. Even after changing wheels, the overall diameter reduction of ≈ 3.7% places this swap in the borderline range, which may affect speedometer accuracy, ride height, and vehicle calibration. Your vehicle would sit 0.5 inches lower to the ground. For a performance car that is likely already low, this increases the risk of scraping the undercarriage or front splitter. The rim mismatch is a "hard no," and even with the correct wheels, the diameter drop is significant enough to cause calibration concerns.
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