Speedometer Error?

[woofy]

Shouldnt have made a discernable difference in speedo reading as only 4 mill difference in diameter.

Something is strange Maybe look at the other car instead, it might be the problem speedo may be way out on it but then you said you tried yours against a GPS so ?????????????????????????????

I'd take it to the dealer and get them to check it. Having someone with an RS report back to you won't help as they would have been set at the factory to use those wheels and you are comparing oranges with apples.

[Aargh]

I've checked my RS (with 19 inch xtreme's) against a GPS app and seen about a 2% difference (reads 98 on the GPS for an indicated 100).

Sent from my SM-G920I using Tapatalk

[AALocksmiths]

Just last week I had a customer with a MK4 Golf with the same issue. The speedo was showing 91km/h when the actual speed was 100km/h. I verified that the issue was in the cluster as the value can be checked by OBD. If is possible to adjust the needle on the clusters but you have to be careful to not damage the servo motors.

[Gerrycan]

You might want to check odo and rev counter accuracy as well

[Jondalar]

Interesting you should say that, because my wife's Golf 110TDI which I thought had identical gearing shows about 250 RPM more at 100 km/hr...

You might want to check odo and rev counter accuracy as well

[Jondalar]

Seriously amazing how many either can't see my sig or don't read the thread. Anyhoo, I checked the speed against my Garmin Nuvi GPS today and found that the speedo is either spot on (up to 60 km/hr) or reading 2-3 km/hr high, so all is as it should be. Moral of the story, don't trust iPhone GPS for speed accuracy...

[Hillbilly]

Seriously amazing how many either can't see my sig or don't read the thread. Anyhoo, I checked the speed against my Garmin Nuvi GPS today and found that the speedo is either spot on (up to 60 km/hr) or reading 2-3 km/hr high, so all is as it should be. Moral of the story, don't trust iPhone GPS for speed accuracy...

Just shows Apple products arent perfect. How could we ever think that.

Had to be something exterior of the car as the wheels wouldnt have done it and as you say are slightly more corrct than it would have been before.

Usually speedos are linear Like 2 out at 50 4 out at 80 6 out at 100 etc.