Member Since: 07 Mar 2008
Location: Johannesburg
Posts: 53
Calibrate 'computer' for tyre size
I have received conflicting information from LR on whether there is a simple 'calibration' possible if a non-standard tyre size is used. In my case I have 265/60 R18 fitted which I calculate to be 1.5% larger than the stock 255/60 R18. I was told by a LR technical guy that it is possible to set the vehicle up for such non-standard sizes (within reason). But the technicians at my dealership know nothing about this and say that it is possible to tell the vehicle whether 17" or 18" rims are being used, but nothing more.
It seems to me that such a calibration would make sense and would be straightforward to implement through software. Any ideas on whether this is or is not possible? While this may or may not be a big deal with just a 1.5% difference, what if I fit BFG ATs at 265/70 R17 which would then be 5.5% too big?
Any inspiration most welcome.
Nick
2nd Apr 2008 2:31 pm
wiggs
Member Since: 03 Sep 2006
Location: Manchester
Posts: 14372
I have AT2's 265/70 R17 and according to my gps speed camera they are vertially spot on .
Were as normal 19" standard wheels and tyres are reading about 4mph out when doing 80mph (speedo reading 76mph)G4 Gone ...but not forgotten
2nd Apr 2008 2:56 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
There's an IDS function to calibrate for non-standard tyre size - not yet available on Autologic...
2nd Apr 2008 3:57 pm
nickm
Member Since: 07 Mar 2008
Location: Johannesburg
Posts: 53
10forcash - thanks, but could you translate that into english for us mere mortals please ?
2nd Apr 2008 4:09 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
The dealers have the ability to re-calibrate the D3 to non- standard tyre size using IDS (Integrated diagnostic system), independents using the Autologic diagnostic system will have to wait until this functionality is added to the software!
2nd Apr 2008 4:17 pm
nickm
Member Since: 07 Mar 2008
Location: Johannesburg
Posts: 53
OK, thanks 10forcash. Perhaps the dealers here in SA don't have IDS, although I would have thought that they do.
I presume that the calibration ensures that any systems that monitor the wheels (ABS etc?) are not confused by non-standard tyres, and that the mileage reading will be accurate?
FFRR you can do a cal. from the sat nav screen - got bored in traffic one morning "To finish first, one first has to finish ...."
2nd Apr 2008 7:55 pm
nickm
Member Since: 07 Mar 2008
Location: Johannesburg
Posts: 53
90BHP wrote:
FFRR you can do a cal. from the sat nav screen - got bored in traffic one morning
OK, now I am really intrigued, tell me more...
2nd Apr 2008 8:01 pm
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18561
You can do the same with the D3 satnav, I think it's used internally within the sat nav as part of the algorithm to confirm speed when the GPS signal is lost.
I don't think it's the same calibration value that the vehicle itself uses from the Car Configuration File to convert the wheel rotation information to a true wheel speed.06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
2nd Apr 2008 8:02 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 73078
Hi Martin, long time no see!!!
2nd Apr 2008 8:03 pm
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
The sat-nav 'calibration' compares the vehicle signals to GPS signals, if you are running wheels & tyres with a non-standard rolling diameter this calibration will always be a compromise and will not alter the speedo calibration, the IDS setting will change the speedo calibration to be more accurate
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on whether there is a simple 'calibration' possible if a non-standard tyre size is used. In my case I have 265/60 R18 fitted which I calculate to be 1.5% larger than the stock 255/60 R18. I was told by a LR technical guy that it is possible to set the vehicle up for such non-standard sizes (within reason). But the technicians at my dealership know nothing about this and say that it is possible to tell the vehicle whether 17" or 18" rims are being used, but nothing more.
?
