275/70R18vs285/70R17
Proportional side-by-side visual comparison, dimensional specs, speedometer calibration, and fitment guide.
Comparison Summary & Verdict
Comparing 275/70R18 (baseline) to 285/70R17 (target):The 285/70R17 is 0.45" shorter in overall diameter (-1.36%) and 0.39" wider.
Side-by-Side Dimension Specifications
Full dimensional metrics calculated according to ISO standardized tire formulas.
| Specification | 275/70R18 (Stock) | 285/70R17 (Target) | Difference (Delta) |
|---|---|---|---|
| Overall Diameter | 33.16" (842 mm) | 32.71" (831 mm) | -0.45" (-1.36%) |
| Section Width | 10.83" (275 mm) | 11.22" (285 mm) | +0.39" (+10 mm) |
| Sidewall Height | 7.58" (193 mm) | 7.85" (199 mm) | +0.27" |
| Circumference | 104.17" (2646 mm) | 102.76" (2610 mm) | -1.41" |
| Revolutions per Mile | 627 revs/mi | 636 revs/mi | +9 revs/mi |
| Wheel Rim Diameter | 18" | 17" | -1" (Requires different wheels) |
| Recommended Rim Width | 7.4" – 9.6" | 7.7" – 10.0" | n/a |
Speedometer & Odometer Calibration Table
Because vehicle speedometers measure axle rotation, changing tire circumference alters speed readings. When switching from 275/70R18 to 285/70R17:
| Actual Speed (GPS) | Speedometer Reading on 285/70R17 | Variance / Error |
|---|---|---|
| 20 mph | 20.3 mph | +0.3 mph |
| 30 mph | 30.4 mph | +0.4 mph |
| 45 mph | 45.6 mph | +0.6 mph |
| 60 mph | 60.8 mph | +0.8 mph |
| 70 mph | 71.0 mph | +1.0 mph |
| 80 mph | 81.1 mph | +1.1 mph |
Fitment & Practical Considerations
Clearance & Rubbing
Because 285/70R17 has very similar dimensions to 275/70R18 (only 0.45" diameter difference), clearance issues or fender rubbing are extremely unlikely on stock suspension.
Gearing & Acceleration
Gearing and acceleration changes will be negligible between these two sizes.
Wheel & Rim Width
Note: 275/70R18 requires a 18" wheel, while 285/70R17 requires a 17" wheel. You must purchase new wheels to make this swap.
Official Calculation Standards & References
All dimension formulas, revs/mile conversions, rim width brackets, and speedometer error deltas on Tire Visualizer are calculated strictly according to international automotive engineering standards:
ISO 4000-1 metric tire dimensional standards, section width ratios, and approved measuring rim definitions.
North American standards for overall tire diameter, static loaded radius, and revolutions-per-mile benchmarks.
Federal motor vehicle safety standards governing pneumatic tire sizing, load indices, and speedometer tolerance limits.
Engineering standards (SAE J2047 & J1982) for dynamic tire rolling radius and speedometer calibration accuracy.
Frequently Asked Questions: 275/70R18 vs 285/70R17
Can I replace 275/70R18 with 285/70R17?
Yes. The diameter difference between 275/70R18 and 285/70R17 is -1.36%, which is within the industry standard ±3% safety margin. It is generally a safe direct replacement without requiring speedometer recalibration or suspension modifications.
How does 285/70R17 affect my speedometer compared to 275/70R18?
When driving at an actual speed of 60 mph on 285/70R17, your speedometer will read 60.8 mph (a difference of -0.8 mph). Your vehicle will be traveling slightly slower than indicated.
Will 285/70R17 change my vehicle's ride height?
285/70R17 has an overall diameter of 32.71" compared to 33.16" on 275/70R18. This will change your ground clearance by -0.22 inches (lower).
What wheel rim width is needed for 285/70R17?
For 285/70R17, the recommended wheel rim width range is typically 7.7" to 10.0" wide, mounted on a 17" diameter wheel.
Compare Other Tire Sizes
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