All brands calibrate the speedo higher. Some are more conservative than the others. With the two Corollas at home, my tires are slightly bigger:
- On the 2007 Corolla, i changed from OEM 185/70R14 to OEM rims with 205/60R15 and now my speedo reading and GPS is almost spot-on (119kph GPS, 120kph speedo).
- On the 2012 Corolla, we changed from 195/65R15 to 215/50R17 and the speedo reading is 118kph GPS versus 120kph speedo. Before that, the discrepancy was roughly 5-6kph.