Does anyone else have this problem?

When I set my cruise control at say 70 on the LCD, my speedo never reads the same - actually quite a bit slower.

How do I recalibrate or is this a case of TADTS  Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

Anyone? Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

the speedo needle should read a littel higher...but the speed can fluxiate and isnt "set" so you can at times be going a little slower or faster (hence the bottom display may say 69 when cruise is set to 70 and the speedo needle could show 70 or 71

All fine - you cant calibrate anyway. Mike

2014 Facelift Discovery

rm0rgan wrote:

Does anyone else have this problem?

When I set my cruise control at say 70 on the LCD, my speedo never reads the same - actually quite a bit slower.

How do I recalibrate or is this a case of TADTS

Mine is the same, complained about it from day one but the dealer said they could do nothing about it. to get the speedo to read 70km/h I have to set 74km/h on the cruise, for 120km/h I have to set 126km/h on the cruise.
Also on a related topic with the original wheels/tyres when the speedo reads 70 km/h the GPS reads 68km/h which compared with other cars I have driven is fairly accurate, with my 19" wheels with the 255/55 MT/R tyres 70km/h on the speedo gives 71km/h on the GPS

On my MG I can enter the service menu on the instrument cluster and re-calibrate the speedo if I really wished, there is a list of offsets for both the speedo and for the inertial navigation counting the pulses from the ABS sensor to send to the sat nav. Sons of dogs come hither and get flesh
Clan Cameron

Thanks for the answers - I guess its just a case of TADTS then.

Its slightly annoying though as I used to set the Cruise at 30 to ensure I stuck to the speed limit in town, but to be doing an indicated 25/26 when the cruise is set to 30 makes me feel im holding up the traffic!

Still, better to be going below 30 than over it  Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

Mine is only a few MPH out which is what it should be

I wonder if the dealers havent set your tyre size setting properly as it should been massively different Mike

2014 Facelift Discovery

rm0rgan wrote:

Thanks for the answers - I guess its just a case of TADTS then.

Its slightly annoying though as I used to set the Cruise at 30 to ensure I stuck to the speed limit in town, but to be doing an indicated 25/26 when the cruise is set to 30 makes me feel im holding up the traffic!

Still, better to be going below 30 than over it

I did wonder this as it has the 20" supercharger wheels on it. Is this something I can check somehow on the car - maybe a menu somewhere?
 Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

The 255/50 R19" tyres are the same diameter as the 275/40 R20" tyres so there should be no speedometer correction needed.
I have 255/55 R19" tyres for off road use and they are a little taller in diameter so I have to take that into account when reading the speedometer. Sons of dogs come hither and get flesh
Clan Cameron

Ah - I was wondering that as I was writing my last reply/question - thanks for confirming.  Wife's Car: BLACK RRS TDV8 HSE with all the bits
My Car: Lotus Exige S2 PP & TP )

I recall the XF had a facility to recalibrate to tyre size, I guess it may dribble over to LR at some point. 08 2.7 RRS "S"
Td5 110......very modified
RS 5
Kawasaki ZX12R me, it's quick !

They never match exactly when changing rim size.

The 20's read slightly faster, the 22's slower

If not, why do LR tell the gearbox module what alloy size is on the car if it doesn't effect the rolling circum slightly.

With my 22's the speedo is 1mph SLOW and the cruise control is 3mph FAST RRS gone
Audi SQ5...Gone Audi Q7 S-Line 240 3.0TDI Gone
Audi A6 Allroad Sport 270 3.0TDI

on the 80scool (Toyota Landcruiser) forum a few years ago they did a test to see if there was any diffrence between diffrent aspect ratio tyres with the same diameter and how it would affect speedo readings, they also did a test to see if there was a diffrence between full pressure in the tyres and airing them down and they found no diffrence in the speedo reading. They did not test the tyres at high speed tho as they were really only intrested in the results for sand driving and it was a good excuse for a meet and a few tinnies  Sons of dogs come hither and get flesh
Clan Cameron

interesting, but on same rim diameter you say... which would make sense, the tyre profilel is a % of the tyre width so there is ltd width that can be fitted to the same car before the wall is changed significantly.

With a 19" alloy and a 22" alloy the profile changes by 2.77cm, that's a big flex difference between a 35 profile and a 55 profile and also results in a rolling radius difference of 6cm RRS gone
Audi SQ5...Gone Audi Q7 S-Line 240 3.0TDI Gone
Audi A6 Allroad Sport 270 3.0TDI

I know that my 110 speedo is bang on with my Garmin with it's oversize tyres on it (285/75/16 BFG M/T's) and have seen some horrendous errors on bike speedo's because of course the faster you go the bigger the difference, in one case @ 90mph it was under by 10 mph so we where pleasantly impressed when we found this out because it achieved an indicated 180 so in reality nudged 200 I think manufacturers ought to be able to design a system that is GPS linked and updates the speedo on a regular basis. 08 2.7 RRS "S"
Td5 110......very modified
RS 5
Kawasaki ZX12R me, it's quick !