Speedometer calibration?
#16
RL Community Team
Rennlist Member
Rennlist Member
Reviving this old thread.
I bumped it up to first page so someone who is looking for it can see it.
I bumped it up to first page so someone who is looking for it can see it.
Last edited by Carlo_Carrera; 05-16-2022 at 11:06 AM.
#17
My 2003 Targa has 285/30R18 on rear, 225/40R18 front. It has upgraded stock 18” Porsche rims. My build sheet shows the 18s. Is this the correct tire size or could I go a bit bigger? Incidentally, I am off reading low by 7 Kmh at 100 Kph. Is there a programmer I can use to address this, speed app on my phone and Waze both verify, digital speed signs also.
#19
Race Director
I don't know about newer Corvettes, but on my '96 C4, I had to use the HyperTech PPIII to change adjust the speedo for the gearing differences when I swapped the D33 for a D44 with 3.73 gearing. Maybe newer cars with built-in GPS can auto-calibrate, but my older Corvette definitely needed to be tweaked. The digital speedo now perfectly matches GPS-indicated speed...
As far as the 996 - my 996 has ALWAYS indicated a few MPH faster than actual speed using the digital and analog gauges. I thought this was a known issue/fact about the 996 - there are countless threads on the Interwebs about it. As far as I know, there is no way to correct for this. An old thread in this very forum from 2013 (https://rennlist.com/forums/996-foru...naccuracy.html) suggests "European regulations mandate that speedos not show less than actual. So european cars have built in errors ( - 3mph) to comply."
As far as the 996 - my 996 has ALWAYS indicated a few MPH faster than actual speed using the digital and analog gauges. I thought this was a known issue/fact about the 996 - there are countless threads on the Interwebs about it. As far as I know, there is no way to correct for this. An old thread in this very forum from 2013 (https://rennlist.com/forums/996-foru...naccuracy.html) suggests "European regulations mandate that speedos not show less than actual. So european cars have built in errors ( - 3mph) to comply."
Last edited by 5CHN3LL; 05-16-2022 at 02:01 PM.
#20
Rennlist Member
I don't know about newer Corvettes, but on my '96 C4, I had to use the HyperTech PPIII to change adjust the speedo for the gearing differences when I swapped the D33 for a D44 with 3.73 gearing. Maybe newer cars with built-in GPS can auto-correct, but my older Corvette definitely needed to be tweaked. The digital speedo now perfectly matches GPS-indicated speed...
As far as the 996 - my 996 has ALWAYS indicated a few MPH faster than actual speed using the digital and analog gauges. I thought this was a known issue/fact about the 996 - there are countless threads on the Interwebs about it; as far as I know, there is no way to correct this.
As far as the 996 - my 996 has ALWAYS indicated a few MPH faster than actual speed using the digital and analog gauges. I thought this was a known issue/fact about the 996 - there are countless threads on the Interwebs about it; as far as I know, there is no way to correct this.
#21
Race Director
<edit>
don't pay attention to the village idiot.
Also, I'm the village idiot...too dumb to know I got necrothreaded. I'l be in the corner counting my thumbs if anyone needs me.
</edit>
2022 - 2013 is 9 the last time I checked...
Regardless, the internet is awash with similar posts.
https://www.theglobeandmail.com/glob...ticle11487709/
https://www.northamericanmotoring.co...-accuracy.html
https://www.caranddriver.com/feature...meter-scandal/
...
don't pay attention to the village idiot.
Also, I'm the village idiot...too dumb to know I got necrothreaded. I'l be in the corner counting my thumbs if anyone needs me.
</edit>
2022 - 2013 is 9 the last time I checked...
Regardless, the internet is awash with similar posts.
https://www.theglobeandmail.com/glob...ticle11487709/
https://www.northamericanmotoring.co...-accuracy.html
https://www.caranddriver.com/feature...meter-scandal/
...
Last edited by 5CHN3LL; 05-16-2022 at 04:47 PM.
#22
Rennlist Member
2022 - 2013 is 9 the last time I checked...
Regardless, the internet is awash with similar posts.
https://www.theglobeandmail.com/glob...ticle11487709/
https://www.northamericanmotoring.co...-accuracy.html
https://www.caranddriver.com/feature...meter-scandal/
...
Regardless, the internet is awash with similar posts.
https://www.theglobeandmail.com/glob...ticle11487709/
https://www.northamericanmotoring.co...-accuracy.html
https://www.caranddriver.com/feature...meter-scandal/
...
The following users liked this post:
TheChunkNorris (05-16-2022)
#24
Rennlist Member
#25
Rennlist Member
Originally Posted by mhoefer;[url=tel:18146395
18146395]I did confirm, for the 18" rim upgrade my car has stock, these are the correct size tires front and back. Still, 7 Kph off seems a lot, programmer?
The wheel and tire sizes on my car, I believe, are stock.
Wheels & Tires Sizes:
Front 225/40ZR18
Rear 265/35ZR18
Tire Pressures:
Front: 36psi
Rear: 44psi
Ran a calculator comparing what you have to mine and looks like the total diameter is different:
Last edited by Mike Murphy; 05-16-2022 at 09:21 PM.
#26
Rennlist Member
It seems like my speedometer is reading between 3 and 5 MPH on the high side (i.e. showing faster than I'm actually going). This is based on readings from a couple of those radar signs that show your speed. Does anyone know if the dealers can do a good job of calibrating the speedometer? Any other thoughts on calibration?
Drive on!
Jim
Drive on!
Jim
Last edited by SealG996; 05-17-2022 at 12:07 AM. Reason: Typo