My IID BT is not yet registered but I'm raring to go when Pat sends me the unlock code.
First job is to recalibrate to allow for the 245/70 R17 tyres I have fitted.
Presumably I adjust the Tyre Dynamic Rolling Radius but:-
To what value to allow for the above tyres
Edited to add: I have just had a suggestion that tyre diameter is 774mm (thus radius 387mm) - is this correct I wonder - it sounds about right? ; and
What further adjustment should be made to allow for the speedometer which over-reads in any event?
Will changing the the Tyre Dynamic Rolling Radius alter both speedometer & odometer - I assume so.
Presumably this will also make the MPG & Range displays more accurate?
Thanks in advance.
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
Consensus is to leave well alone on a D3 (D4 is easily tweaked)... Current: Discovery 3 06MY (55 reg) HSE Auto Zambezi Silver Allisport Fast Road Intercooler, V8 Brakes, Silicone IC Hoses, EGRs Blanked, Remapped, De-Cat pipe, FBHIC
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4th Oct 2015 5:19 pm
Nodge68
Member Since: 05 Sep 2014
Location: Newquay
Posts: 1014
I wasn't aware that the rolling radius could be altered with the IID. When I went from 17s to 18s, it corrected the slightly optimistic speedo. Freelander SE 2005 Auto.
D3 TDV6. Gone.
"Consensus is to leave well alone on a D3" - why, could you expand this statement please?
TIA
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
4th Oct 2015 6:21 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Critical parameter that is part of the CCF health-check.
I'd leave it alone. In fact I am surprised that it has been unlocked for regular tool users. I had recommended otherwise.
Land Rover - Turning Drivers into Mechanics Since 1948
Noted - it may not be unlocked for regular tool users, I'm still awaiting an unlock code.
Regards
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
4th Oct 2015 6:31 pm
koko118
Member Since: 14 Jan 2014
Location: Europe
Posts: 5
Changing tyre diameter in ccf will change the air suspension height, too.
23rd Nov 2015 9:59 pm
MarkOne
Member Since: 23 Jul 2011
Location: County Antrim
Posts: 3345
I asked about this before, it's not a million miles considering I'm running 285/50/20. It doesn't bother me, and I believe it could cause more trouble than it worth.
Member Since: 14 Jan 2014
Location: Europe
Posts: 5
Quote:
I've not seen that happen.
Measure the height before and after changing tyre diameter with SDD, and will see there is a little difference.
24th Nov 2015 10:11 am
HughMartin
Member Since: 30 Mar 2008
Location: Aberdeenshire
Posts: 751
I have a 10% error on my D4 odometer but couldn't find any reference in the IID user manual nor function on the tool itself to check or change the tyre circumference value. I was sure it was available when I had my D3. I checked with GAP and Patrick says the function should be available in a few months. Was it available previously or am I imagining it?
25th Feb 2016 5:33 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Please do not adjust the rolling circumference even if the tool makes it available. As mentioned previously, my recommendation to Pat was not to include that option on the regular BT units.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 30 Mar 2008
Location: Aberdeenshire
Posts: 751
Why do you say that Robbie?
What other alternative do I have to correct the odometer error?
25th Feb 2016 6:19 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
As mentioned previously, it is a critical parameter used for an integrity check of the CCFs.
Whilst the speedo and trip computer have errors built in the odometer has always appeared pretty accurate to me.Land Rover - Turning Drivers into Mechanics Since 1948
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Allisport Fast Road Intercooler, V8 Brakes, Silicone IC Hoses, EGRs Blanked, Remapped, De-Cat pipe, FBHIC
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