225/40R18 speedometer error table
Speedometer change from tire size: calculation and limits
This reference page compares 225/40R18 with nearby popular sizes and shows how each alternative changes indicated speed. The calculation uses the same deterministic tire-geometry engine as the live calculator.
| Candidate size | Overall diameter | Diameter difference | Indicated 100 reads as | Verdict | Compare |
|---|---|---|---|---|---|
| 225/40R18 | 25.09 in | 0% | 100 mph | Close match | Open calculator |
| 255/35R18 | 25.03 in | -0.24% | 99.8 mph | Close match | Compare |
| 195/65R15 | 24.98 in | -0.42% | 99.6 mph | Close match | Compare |
| 225/35R19 | 25.20 in | +0.46% | 100.5 mph | Close match | Compare |
| 225/45R17 | 24.97 in | -0.46% | 99.5 mph | Close match | Compare |
| 195/60R16 | 25.21 in | +0.50% | 100.5 mph | Close match | Compare |
| 205/55R16 | 24.88 in | -0.83% | 99.2 mph | Close match | Compare |
| 215/55R16 | 25.31 in | +0.89% | 100.9 mph | Close match | Compare |
| 225/50R16 | 24.86 in | -0.91% | 99.1 mph | Close match | Compare |
| 235/45R17 | 25.33 in | +0.96% | 101.0 mph | Close match | Compare |
| 235/40R18 | 25.40 in | +1.26% | 101.3 mph | Close match | Compare |
| 195/70R14 | 24.75 in | -1.35% | 98.7 mph | Close match | Compare |
| 215/50R17 | 25.46 in | +1.51% | 101.5 mph | Close match | Compare |
Reference pages are limited to the public TireFitLab size corpus. The long tail stays gated until demand data supports expansion.
How to read the table
Positive speedometer error means the vehicle travels faster and further than indicated. The tolerance verdict only checks overall diameter; it does not verify load rating, clearance, wheel fitment or local approval.
Related references
- Speedometer error calculator
- Tire size calculator
- Speedometer change from tire size: calculation and limits
Seasonal check
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