Your tyre size should make it read 4-6% high depending on new or worn tyres. Also, different makes of tyre have different rolling radius for the same size. Then on top of that mechanical speedos on european vehicles have an allowable tolerence of -0/+10% in reading so that it can read up to 10% higher given all other factors are perfectly sized. Its a safety thing so that you ought not to exceed any speed limits if you adhere to what your speedo reads. In general you can see that your speedo only shows an indicative reading, it can't be accurate because there are too many variables.
Clive
|