275/70R18 vs 285/65R18
285/65R18 is 0.6 inches shorter and 0.4 inches wider. When your speedometer says 60 mph, you'd really be doing 59.0.
I have 275/70R18
I'm looking at 285/65R18
Close match
0.6 in shorter. At 60 mph on the speedometer you'd really be doing 59.0.
- Within the 3% height difference most tire shops consider safe.
275/70R18 now 285/65R18 newTo scale
At an indicated 60 mph you're really doing 59.0 mph
−0.57″
Height
+0.39″
Width
−0.29″
Sidewall
All measurements
| 275/70R18 | 285/65R18 | Change | |
|---|---|---|---|
| Overall height | 33.16″ | 32.59″ | −0.57″ |
| Section width | 10.83″ | 11.22″ | +0.39″ |
| Sidewall height | 7.58″ | 7.29″ | −0.29″ |
| Wheel size | 18″ | 18″ | same |
| Distance per turn | 104.17″ | 102.37″ | −1.79″ |
| Turns per mile | 608 | 619 | +11 |
Speedometer after switching
Your speedometer is calibrated for 275/70R18. On 285/65R18:
| Speedometer says | You're really doing |
|---|---|
| 25 mph | 24.6 mph |
| 35 mph | 34.4 mph |
| 45 mph | 44.2 mph |
| 55 mph | 54.1 mph |
| 65 mph | 63.9 mph |
| 75 mph | 73.7 mph |
What changes on the vehicle
- Ride height goes down about 0.29″ (half the height difference).
- The tire turns 11 more times per mile, so your odometer will read high by about 1.7%.
- The sidewall is 0.29″ shorter, on the same wheels.