Speedo Calibration

[Disco4 Member Find all posts View Profile Close Disco4]

Guys

First of all an apology if covered before.

After research here I have narrowed down my tyre choices to 2 sizes.

Either 265 x 70 x 17 or 275 x 70 x 17.

The 265's should result in an accurate speedo allowing for inbuilt and allowable tolerances.

However the 275's will most probably result in a marginally lower speed being displayed than what is the actual road speed.

My estimate will be 3 to 4 km/h at 100 km/h which with a lack of concentration is enough to get you booked.

Can the speedo calibration be changed by entering new tyre size data.
If so who could do that?

Tru Speed make such a Black box for Discovery 2's.

Are there any other options other than remembering to deduct speed off the speedo?

Regards

Disco4

[Derb Senior Member Find all posts View Profile Close Derb]

Hi Boss. Jaycar sell an electric speedo gizmo for recalibrating error. Cheers.

[4wd Supplies Member Find all posts View Profile Close 4wd Supplies]

hey mate, are you 100% sure your speedo is correct to start with, might be worth doing a little check against a gps or alike as most cars these days come from the factory with upto a 10% difference.

[kieranu Member Find all posts View Profile Close kieranu]

Yeah - the speedo on my 150 is at least 5% off so I can comfortably go 110 (by the speedo) in a 100 zone and know I'm not going to get clocked. Get the 265/70s on next week and I'll let you know the difference but it should bring the speedo to read just slightly over the true speed.

[rbert Lurker Find all posts View Profile Close rbert]

I found with mine that my Prado's computer as read from an ECU reader, reads the same as a GPS and a radar speed advisory station, but the speedo reads 4kmh over actual speed. Mr Toyota in there wisdom obviously build a deliberate error into the speedos

[Peterpilot Avid PP Poster! Find all posts View Profile Close Peterpilot]

hey mate, are you 100% sure your speedo is correct to start with, might be worth doing a little check against a gps or alike as most cars these days come from the factory with upto a 10% difference.

Earlier 120 series Prados like my 2004 model speedo reads spot on with 265/65 tyres. Later 120 series and all 150 series Prado speedos read spot on with 265/70 tyres.

[starbuck76 Member Find all posts View Profile Close starbuck76]

I found with mine that my Prado's computer as read from an ECU reader, reads the same as a GPS and a radar speed advisory station, but the speedo reads 4kmh over actual speed. Mr Toyota in there wisdom obviously build a deliberate error into the speedos

To comply with ADR speedos must not read slower than actual speed, which is why from factory the speedo is 4 or 5 kmh out but the car computer is correct.

[rbert Lurker Find all posts View Profile Close rbert]

yeah thought 2 kmh would have been enough, but 4k's out I find annoying as I tend to drive at a higher speed to compensate for the error. Would much prefer to know that what I'm seeing on the speedo is the actual speed the car is doing.
guess its to cover themselves for different size tyres

[yowie Advanced Member Find all posts View Profile Close yowie]

yeah thought 2 kmh would have been enough, but 4k's out I find annoying as I tend to drive at a higher speed to compensate for the error. Would much prefer to know that what I'm seeing on the speedo is the actual speed the car is doing.
guess its to cover themselves for different size tyres

You will also have a different speedo reading between a brand new tyre and a worn tyre!

It is better to be reading under than over the actual ground speed. A GPS unit will give a more accurate reading, when used on a flat straight section of road.

The only other thing is to travel a few k/h above the actual speedo reading to be at the speed you require.

Yowie.

[Scott Montgomery Lurker Find all posts View Profile Close Scott Montgomery]

I fitted a Bogaard speed sensor from PJL Diesel Electric, thought is wasnt working right as it was 4Km under the speedo reading, until i read this blog
http://www.pjldiesel.com.au/product.php?part_id=747707

[kieranu Member Find all posts View Profile Close kieranu]

With the 265/70R17 tyres my speedo reading has gone from about 4% out to only about 1% out [which is perfectly acceptable]

[Skoeter Lurker Find all posts View Profile Close Skoeter]

My vehicle has the option of an auto speedo calibration via the multi media touch screen. I am not too sure which models has this function, but it is worthwhile to check the owner's manual before buying any gizmos.

Cheers

[busha Lurker Find all posts View Profile Close busha]

Guys
.......
Can the speedo calibration be changed by entering new tyre size data.
If so who could do that?

Are there any other options other than remembering to deduct speed off the speedo?

Regards

Disco4

I have installed Yellow Box V5 with splice wiring (solder connection) on my Grande 120, tested and calibrated speedometer for bigger tyres. My full installation information is in this thread:
http://www.pradopoint.com/showthread...=certification
The Yellow Box V5 works fine and I am very happy and also particularly thankful to Jenny at Yellow Box who has been excellent in finding the correct solution. For about $79.95USD, or about $76.40AUD, it is a very good value. Thier website and contact details:
www.YellR.com
[email protected]
Cheers
AB

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Busha's install link....
http://www.pradopoint.com/showthread...l=1#post364835
Cheers....PS I went thru the certification process for my 90 series, luckily the speedo was accurate with larger wheels.

[rugbynut Lurker Find all posts View Profile Close rugbynut]

I was on a long trip the other day. Car in CC at 115 km and lots of traffic sitting at the same or slightly faster speed? So i reset the ave speed indicator to see if it was different. It was different and read 110? Is this speed calculated by the gps unit and not the dash speedo? .

Seems after reading this blog in terms of reading about 5% over the actual speed. What really gave it away was all the other traffic was going the same speed. Not likely here in wa govern the fines etc etc haven't been able to checkmwith a separate gps as yet

Cheers