305/60R18 vs 305/65R17
305/65R17 is a safe swap for 305/60R18 by the usual ±3% rule: the diameter differs by +0.62%.
Speedometer and odometer
With 305/65R17 on a car calibrated for 305/60R18, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.6%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.3 mph |
| 60 mph | 60.4 mph |
| 70 mph | 70.4 mph |
| 80 mph | 80.5 mph |
Other sizes close to 305/60R18
- 305/60R18 vs 275/65R18-1.03%
- 305/60R18 vs 275/70R18+2.31%
- 305/60R18 vs 285/70R17+0.92%
- 305/60R18 vs 265/65R18-2.61%
- 305/60R18 vs 265/70R18+0.61%
- 305/60R18 vs 255/70R18-1.09%
- 305/60R18 vs 255/65R18-4.19%
- 305/60R18 vs 285/65R18+0.55%
- 305/60R18 vs 33x12.50R18+1.82%
- 305/60R18 vs 285/60R18-2.92%
- 305/60R18 vs 275/70R17-0.78%
- 305/60R18 vs 305/65R18+3.71%
Questions
Can I replace 305/60R18 with 305/65R17?
305/65R17 is a safe swap for 305/60R18 by the usual ±3% rule: the diameter differs by +0.62%.
What's the difference between 305/60R18 and 305/65R17?
305/65R17 is 0.20" taller and 0 mm wider; the sidewall is +0.60". At an indicated 60 mph you'd actually be doing 60.4 mph.
Will 305/65R17 fit on 305/60R18 wheels?
No — 305/60R18 needs a 18" wheel and 305/65R17 a 17" wheel. This is a plus/minus-size swap that changes wheels too.