185/65R15 vs 245/45R16
245/45R16 is a safe swap for 185/65R15 by the usual ±3% rule: the diameter differs by +0.87%.
Speedometer and odometer
With 245/45R16 on a car calibrated for 185/65R15, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.3 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.6 mph |
| 80 mph | 80.7 mph |
Other sizes close to 185/65R15
Questions
Can I replace 185/65R15 with 245/45R16?
245/45R16 is a safe swap for 185/65R15 by the usual ±3% rule: the diameter differs by +0.87%.
What's the difference between 185/65R15 and 245/45R16?
245/45R16 is 0.21" taller and 60 mm wider; the sidewall is -0.39". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 245/45R16 fit on 185/65R15 wheels?
No — 185/65R15 needs a 15" wheel and 245/45R16 a 16" wheel. This is a plus/minus-size swap that changes wheels too.