285/65R18 vs 285/70R17Tire Size Comparison
The 0.4% diameter difference is within the accepted 3% tolerance.
Comparison Details
Speedometer Correction
When switching from 285/65R18 to 285/70R17, your speedometer will differ from actual speed.
| Speedometer | Actual Speed | Difference |
|---|---|---|
| 30 km/h | 30.1 km/h | +0.1 km/h |
| 40 km/h | 40.1 km/h | +0.1 km/h |
| 50 km/h | 50.2 km/h | +0.2 km/h |
| 60 km/h | 60.2 km/h | +0.2 km/h |
| 70 km/h | 70.3 km/h | +0.3 km/h |
| 80 km/h | 80.3 km/h | +0.3 km/h |
| 90 km/h | 90.3 km/h | +0.3 km/h |
| 100 km/h | 100.4 km/h | +0.4 km/h |
| 110 km/h | 110.4 km/h | +0.4 km/h |
| 120 km/h | 120.4 km/h | +0.4 km/h |
| 130 km/h | 130.5 km/h | +0.5 km/h |
Vehicles Using These Sizes
Vehicles with 285/65R18
Vehicles with 285/70R17
Individual Tire Size Details
Practical Guidance
Switching from 285/65R18 to 285/70R17 is within the industry-accepted 3% diameter tolerance. Your speedometer, ABS, and traction control should function normally. Note: these sizes require different rim diameters (18" vs 17"), so you will need different wheels.
The 3% diameter tolerance is a widely accepted industry guideline referenced by the ETRTO and most vehicle manufacturers. When in doubt, consult your vehicle's owner's manual or a qualified tire professional. For U.S. tire safety standards and recalls, see the NHTSA Tire Safety page.
Frequently Asked Questions
Safe. The overall diameter differs by 0.37%, width changes by 0mm.
Speedometer error will be 0.37%. At an indicated 100 km/h, actual speed is about 100.4 km/h.
Ground clearance changes by +1.5mm per side.