Re:Fitting larger wheels
#1
02-22-2007, 10:14 PM
Re:Fitting larger wheels
I mentioned a short while ago about possible diff lock as a result of hard braking when wheels have been changed to different diameters from when the X Type left the factory.I couldnt find the thread to add this to the original topic so here is an update after I contacted Jaguars Paul Grantham to explain this (even though rolling diameters may be similar check out the bit about tyre wear
):-
):-
"All on board computers need an accurate wheel speed signal to calculate such things as ABS, DSC and transmission shifts and therefore the correct wheel information has to be programmed into the instrument cluster be means of IDS or WDS.
This is a critical piece of information for correct operation of some of the safety features within the vehicle, the instrument cluster will even make a correction for tyre wear it is that critical."
This is a critical piece of information for correct operation of some of the safety features within the vehicle, the instrument cluster will even make a correction for tyre wear it is that critical."
#2
02-22-2007, 11:15 PM
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RE: Re:Fitting larger wheels
ORIGINAL: BuckMR2
I mentioned a short while ago about possible diff lock as a result of hard braking when wheels have been changed to different diameters from when the X Type left the factory.I couldnt find the thread to add this to the original topic so here is an update after I contacted Jaguars Paul Grantham to explain this (even though rolling diameters may be similar check out the bit about tyre wear):-
I mentioned a short while ago about possible diff lock as a result of hard braking when wheels have been changed to different diameters from when the X Type left the factory.I couldnt find the thread to add this to the original topic so here is an update after I contacted Jaguars Paul Grantham to explain this (even though rolling diameters may be similar check out the bit about tyre wear
):-
"All on board computers need an accurate wheel speed signal to calculate such things as ABS, DSC and transmission shifts and therefore the correct wheel information has to be programmed into the instrument cluster be means of IDS or WDS.
This is a critical piece of information for correct operation of some of the safety features within the vehicle, the instrument cluster will even make a correction for tyre wear it is that critical."
This is a critical piece of information for correct operation of some of the safety features within the vehicle, the instrument cluster will even make a correction for tyre wear it is that critical."
Jim C
#3
02-23-2007, 12:32 PM
Senior Member
RE: Re:Fitting larger wheels
I remember the thread, but the key to it is the TIRE. The info. programmed into the cluster or pcm is actually "RPM" (Revolutions Per Mile) of the tire. Consequently, rim size wouldn't matter, as long as a lower profile tire is used to maintain the same (or close) RPM.
#4
02-23-2007, 04:48 PM
RE: Re:Fitting larger wheels
This is part of the email I sent to him where I mentioned the overall rolling diameter of the wheels:-
[/align]From this I got this reply:-[/align]
[/align]I know what you mean about overall rolling diameter RudyF6 and specifically pointed this out to him but he still says it needs to be programmed in.[/align]
Can you clarify something for me...you mentioned about having to have new (larger) wheel diameters programmed into the message centre if I remember in order to avoid possible damage to the drivetrainpossibly locking up under heavy braking.[/align]Does this need to be done even if the rolling diameter is more or less the same?
All on board computers need an accurate wheel speed signal to calculate such things as ABS, DSC and transmission shifts and therefore the correct wheel information has to be programmed into the instrument cluster be means of IDS or WDS.
#7
02-24-2007, 08:43 PM
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#8
02-24-2007, 09:31 PM
#9
02-25-2007, 08:38 AM
RE: Re:Fitting larger wheels
If it were me and I had fitted different wheels from when it came out of the factoryon mine from what I have been told by the (very knowledgable) Jag man himself I would be contacting my dealer about this programming in of a different wheel size.Wouldnt want my diff to lock up under heavy braking.
#11
03-02-2007, 10:04 PM
RE: Re:Fitting larger wheels
I still don't understand this racer maybe you could put some logic on it...If the overall diameter is the same when you go from 17 to 19 inch what does it matter? As long as the width doesn't increase and it stays at the 7.5" wide and what not why would it matter as long as you keep the profile of the tire right with the equation i.e. 35 series with 19, 40 with 18 and 45 with 17...................
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