GPS Speed display in RNS510?

[gregozedobe]

IIRC the story is that manufacturers are covering themselves for the scenario when an owner fits tyres that are nominally the same size as std but actually have a larger rolling diameter, so the speedo now reads slow. If the speedo was accurate before, they could now be driving along with the speedo indicating right on the spped limit, but their car is actually travelling 3kmh over so they get booked, blame the manufacturer and then sue the manufacturer for causing it. (if in doubt - blame lawyers and the legal system )

[Gav23]

If getting sued for speeding because of driving tyres other than the standard ones that come on the vehicle, why don't they just put a clause or warning in the owner's manual instead? And if getting sued is such a great concern, why doesn't every other car manufacturer have such a massive gap in odometer speed and actual speed?

[BlackSuperb]

I believe the NSW RTA limits for a calibrated speedo is a maximum of 9% over read and 0% under read.

Anything above or below those limits and you need to renew/recalibrate your speedo.

[K1W1]

Speedo calibration is covered by Australian Design Rules not state based road transport authorities. If that is what the NSW RTA are saying then it will be an Australian Standard.

I actually thought they were moving to a +5% allowable error, the previous one was +10%.

Edit:

A quick Google just found this ADR (click for link). I'm not sure whether it's the current standard but if you want to read through on about page 10 you will find this;
"5.3. The speed indicated shall not be less than the true speed of the vehicle. At the test speeds specified in paragraph 5.2.5. above, there shall be the following relationship
between the speed displayed (V1 ) and the true speed (V2).
0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h"

along with a detailed list of the test procedure requirements.

[Maverick]

Speedo calibration is covered by Australian Design Rules not state based road transport authorities. If that is what the NSW RTA are saying then it will be an Australian Standard.

The ADR is based on UNECE 39/00 (Rev 1).

I actually thought they were moving to a +5% allowable error, the previous one was +10%.

It used to be +/- 10%. Victoria and NSW IIRC "overrode" this and only allowed a car to be ~3% under despite cars being allowed under the ADR to be 10% under hence the 3kph leeway in Victoria for speed cameras.

A quick Google just found this ADR (click for link). I'm not sure whether it's the current standard but if you want to read through on about page 10 you will find this;
"5.3. The speed indicated shall not be less than the true speed of the vehicle. At the test speeds specified in paragraph 5.2.5. above, there shall be the following relationship
between the speed displayed (V1 ) and the true speed (V2).
0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h"

along with a detailed list of the test procedure requirements.

That is the current standard.

I have some info here including how to adjust it using Vagcom/VCDS - Volkswagen Speedometer Error Correction.

[Graybags]

Excuse my ignorance but how do you access VAGCOM? Do you need a cable? Laptop?
-Gt

[Swallowtail]

Excuse my ignorance but how do you access VAGCOM? Do you need a cable? Laptop?
-Gt

It's a combination of software and a special cable - www.ross-tech.com will enlighten you...

[K1W1]

It used to be +/- 10%. Victoria and NSW IIRC "overrode" this and only allowed a car to be ~3% under despite cars being allowed under the ADR to be 10% under hence the 3kph leeway in Victoria for speed cameras.

That's not quite correct.
The ADR is still the ADR and vehicles must comply with the ADR.
What Vic and NSW did was to stop accepting the ADR as a defence for speeding so you can be happily driving in one of those states with your speedo showing exactly 100kph but if you are actually travelling at 105kph because your speedo is (legally) reading slow you will get booked and you have no defence.
Also in Victoria at least the allowance is 3kph not 3%. If you are doing 53 in a 50 zone you are okay, 54 and it costs you $146.00, if you are doing 103 in a 100 zone okay but 104 costs you $146.00

[Maverick]

That's not quite correct.
The ADR is still the ADR and vehicles must comply with the ADR.
What Vic and NSW did was to stop accepting the ADR as a defence for speeding so you can be happily driving in one of those states with your speedo showing exactly 100kph but if you are actually travelling at 105kph because your speedo is (legally) reading slow you will get booked and you have no defence.
Also in Victoria at least the allowance is 3kph not 3%. If you are doing 53 in a 50 zone you are okay, 54 and it costs you $146.00, if you are doing 103 in a 100 zone okay but 104 costs you $146.00

Except you do have a defence, if you have you car tested to show that it's reading within the ADR's this is a valid defence. What you can't do is show up in court and claim your speedo can be + or - 10% and expect it to be accepted.