Speedometer Readings v. Actuals

[Las Palmas]

3 hours ago, Linas.P said:

As well it is often important to consider the largest wheels size that was available for the car. For example if Lexus IS250 came with 16", 17" and 18" wheels, then speedometer will be adjusted for 18" wheels (as manufacturer cannot legally sell car which indicates less speed than it is actually doing, thus they have to use largest wheel as reference) at which point it will probably overread by 5%, but if you get lower spec car with 16" wheels then the difference is likely to be 10%. 

Different tyre sizes would not need to change any settings. Above 3 are all within 3% so should not be any problem.

 

[Linas.P]

2 minutes ago, Las Palmas said:

Different tyre sizes would not need to change any settings. Above 3 are all within 3% so should not be any problem.

 

That was kind of my point... manufacturers adjust the speedometer over-read on the largest wheel/tyre they planning to sell the car with and the all the smaller wheels then end-up over-reading by more, but generally the difference between the sizes are too small to take them out of the compliance. At least that would be consistent to my experience, where the model with largest wheels available from manufacturer usually has least difference between stated and real speed.