+3.34%Borderline — noticeable speedometer/odometer error
Speedometer error
With a speedometer calibrated to 235/35R19, fitting 235/45R18 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 41.3 km/h | 25 mph | 26 mph |
| 60 km/h | 62.0 km/h | 37 mph | 39 mph |
| 80 km/h | 82.7 km/h | 50 mph | 51 mph |
| 100 km/h | 103.3 km/h | 62 mph | 64 mph |
| 120 km/h | 124.0 km/h | 75 mph | 77 mph |
Full comparison
235/35R19
Overall diameter647.1 mm · 25.48 in
Section width235 mm · 9.25 in
Sidewall height82.3 mm · 3.24 in
Circumference2032.9 mm · 80.0 in
Revolutions per mile792
Revolutions per km492
235/45R18
Overall diameter668.7 mm · 26.33 in
Section width235 mm · 9.25 in
Sidewall height105.8 mm · 4.16 in
Circumference2100.8 mm · 82.7 in
Revolutions per mile766
Revolutions per km476
+3.34%Borderline — noticeable speedometer/odometer error
Original
Overall diameter647.1 mm · 25.48 in
Sidewall height82.3 mm
Circumference2,032.9 mm
Revolutions / mile791.6
New
Overall diameter668.7 mm · 26.33 in
Sidewall height105.8 mm
Circumference2,100.8 mm
Revolutions / mile766.1
Speedometer & odometer error
The new tire changes overall diameter by +3.34%. With a speedometer calibrated to the original tire, that same percentage is how far the speedometer and odometer read off — a taller tire means your true speed is higher than indicated and the odometer under-counts distance.
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 41.3 km/h | 25 mph | 26 mph |
| 60 km/h | 62 km/h | 37 mph | 39 mph |
| 80 km/h | 82.7 km/h | 50 mph | 51 mph |
| 100 km/h | 103.3 km/h | 62 mph | 64 mph |
| 120 km/h | 124 km/h | 75 mph | 77 mph |
See individual specs: 235/35R19 · 235/45R18. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.