VX Calais - Speedo out, tyre wheel recommendation?

[nathan173]

Hello,
A few problems, maybe all have the same cause.

I've recently bought a VX Callais, its V6 Supercharged, has been owned by a govt dept and old people and has been well looked after and properly serviced.
It has factory 16" Alloys, not sure what tyres are on it (couldn't be bothered going outside at night to check).
Also seems a bit low, scrapes on driveways everywhere when my VT executive didn't have that problem.

My speedo is out, on the highway I noticed I was slower than other drivers so I checked my GPS, it said I was doing 110kph when my speedo showed 118.
I'm assuming my tyres are too small, or could this be another problem?

The 16" rims look a bit small for the car, what Holden wheels would you recommend that will still be classy, I'm not a rev head.

Thanks

 

[07GTS]

changing tyres wont get u anywhere near 8% increase, easiest way is to find a mechanic with the correct scan tool that can change the pulses then its a easy change and your done

 

[nathan173]

I finally got around to talking to a mechanic with the scan tool who then put me on to the holden dealer service dept, the guy didn't know anything about VX's (like whether it had a speedo gear or was electronic) but produced a well worn laminated printout showing me that at 110KPH on my speedo, anything from 110KPH to 125KPH was ADR compliant!
I was lost for words, 125??? Coppers won't pull me over for doing 125?? Yikes.

Do you have more info on the scan tool pulses?

 

[NeddyBear]

16's are a perfect size for the VX, we run 215/60/R16 95V and have her sitting one down from standard and it never touches any of the speed bumps at work.
I reset the speedometer using the meter thingy on the dash so that when I'm doing 95ks the speedometer is showing 100ks and sure cars overtake us all the time
but hey we've never has a ticket and in the end get to where were going just as fast as anyone else.

 

[vr304]

Id try elsewhere to get your speedo sorted, it can definitely be reprogrammed

 

[nathan173]

16's are a perfect size for the VX, we run 215/60/R16 95V and have her sitting one down from standard and it never touches any of the speed bumps at work.
I reset the speedometer using the meter thingy on the dash so that when I'm doing 95ks the speedometer is showing 100ks and sure cars overtake us all the time
but hey we've never has a ticket and in the end get to where were going just as fast as anyone else.

Mine scrapes everywhere, but I live in a hilly town. I am considering swapping the springs out for ones from a vt berlina wreck I have.
My other car is a VT and it has 17's and never scrapes anywhere.

What exactly is the meter thingy on the dash? Maybe that's my problem

 

[nathan173]

I tried a spare speedo from a VT berlina I have, and it is spot on, so I definitely know its in the speedo itself.
Fiddled about with the menu button and accidentally found what looked like a calibration prompt, but was unsure of how to use it.

Then found this: https://forums.whirlpool.net.au/archive/1951166

"speedometer pulses per kilometre for the correct tyre size.
Nominal value is 6250 pulses per km.
• Tyre size 205 65 R15, select 6272 pulses.
• Tyre size 215 60 R15, select 6285 pulses.
• Tyre size 215 60 R16, select 6077 pulses.
• Tyre size 225 50 R16, select 6391 pulses.
• Tyre size 225 55 R16, select 6087 pulses.
• Tyre size 225 60 R15, select 6238 pulses.
• Tyre size 235 45 R17, select 6301 pulses.

or get police mode enabled, and can do it from dash.

Turn the ignition off.
Hold down the MODE button as well as the up

and down buttons on the trip computer.
Turn the ignition on while holding down the
three buttons.
Release the MODE button after 3 seconds,
then release the other two buttons. The
calibration value will now be flashing and C will
be displayed.
The calibration value (in percentage) can now
be adjusted with the up and down buttons. Set to
80% – 120% as necessary.
When the calibration has been achieved, press
the MODE button to lock in the calibration data
and return to the normal display."

So I think that's what NeddyBear was talking about.

Will give it a go tomorrow, then hopefully that problem is sorted and I can drive safely again.