-3.00%Borderline — noticeable speedometer/odometer error
Speedometer error
With a speedometer calibrated to 255/40R22, fitting 295/35R21 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 38.8 km/h | 25 mph | 24 mph |
| 60 km/h | 58.2 km/h | 37 mph | 36 mph |
| 80 km/h | 77.6 km/h | 50 mph | 48 mph |
| 100 km/h | 97.0 km/h | 62 mph | 60 mph |
| 120 km/h | 116.4 km/h | 75 mph | 72 mph |
Full comparison
255/40R22
Overall diameter762.8 mm · 30.03 in
Section width255 mm · 10.04 in
Sidewall height102.0 mm · 4.02 in
Circumference2396.4 mm · 94.3 in
Revolutions per mile672
Revolutions per km417
295/35R21
Overall diameter739.9 mm · 29.13 in
Section width295 mm · 11.61 in
Sidewall height103.3 mm · 4.06 in
Circumference2324.5 mm · 91.5 in
Revolutions per mile692
Revolutions per km430
-3%Borderline — noticeable speedometer/odometer error
Original
Overall diameter762.8 mm · 30.03 in
Sidewall height102 mm
Circumference2,396.4 mm
Revolutions / mile671.6
New
Overall diameter739.9 mm · 29.13 in
Sidewall height103.3 mm
Circumference2,324.5 mm
Revolutions / mile692.4
Speedometer & odometer error
The new tire changes overall diameter by -3%. 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 | 38.8 km/h | 25 mph | 24 mph |
| 60 km/h | 58.2 km/h | 37 mph | 36 mph |
| 80 km/h | 77.6 km/h | 50 mph | 48 mph |
| 100 km/h | 97 km/h | 62 mph | 60 mph |
| 120 km/h | 116.4 km/h | 75 mph | 72 mph |
See individual specs: 255/40R22 · 295/35R21. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.