Looking to run oversize tyres on my FL2 which as a result will have the speedo etc running out.
I reckon that at speedo reading of 70mph I'd be doing a true [gps] 72 mph.
[the milometer and oddometer would also be out].

So, can the speedo be recalibrated on the FL2 and if so how's it done?

The above is no real hassle, but I'd prefer to have it running near accurate.

The maximum rolling circumference that can be set is 2260 mm.
And this by changing values in CCF.

I would imagine that re calibrating a speedo will be 'frowned' upon and may even be illegal? I can imagine many people wanting to re calibrate, especially if on high mileage contracts

I can see the reasoning behind it but in reality it isn't that far out to warrant the bother IMHO.

Many thanks for response Alex.
But how is this done, I take it it's a special piece of equipment (like a Faultmate) that's required ?

@ Paul, but this is to get it reading correctly and not for any illegal gain.
The true difference would be around 5mph at 70.
As normally when travelling at a speedo readout of 70mph, the true speed would be around 67mph.
So at a speedo reading of 70mph, the oversize tyres potentially reading at a true speed of 72mph, hence the 5mph difference.

Btw, With my current 275/45 tyres the speedo and gps speed are the same.

It's ok, I wasn't inferring that was your use, what you are trying to gain is correct, it doesn't take much to wander over a limit and get nabbed, surprised if it can be done, hopefully Alex has a solution for you

275 is a fair old width, do they not catch at all, even when the springs are compressed?

Taking the maximum figure Alex gives of 2260mm then it allows no leeway for oversized tyres, as a standard LR tyre has about 2250mm rolling circumference and is already very close to the maximum value.

@ Taztastic - Yes, my concern was if I was sitting at a speedo reading of 70mph on a monitored section of motorway, i would actually be doing 72mph.


No catching at all..... but that's on Evoque wheels
All the spring compression happens above the tyre, there's no fouling the uprights and there's also no rubbing on lock to lock.
So happy enough with the 275/45, but now trying to push it to 285/50 - hence the reason for raising this thread.


Edited to add:
Thanks EYorkshire, so looks like no recalibration would be available then.



Last edited by ronp on 2nd Jan 2015 7:46 pm. Edited 1 time in total

Yes, with any tool that can process (read/modify/write) the CCF on FL2.

But unfortunately, I believe that 275/45 dimension will give you way much than 2260 mm circumference.
With an alloy of 20 inches will give you about 2280 mm.

Click image to enlarge

Thanks Alex
Happy enough with the readings on the 275/45 (as mentioned, that's giving me a 'true' reading.)

But the 285/50 would give a rolling circumference of 2391.63.
So as mentioned, that's way out of the parameters for re calibrating.

One question - on running oversize tyres what would that do to the displayed miles on the milometer and also the displayed mpg.
Does it over record or under record.

I know it's basic and should be easy, but I cant seem to get my head around that one.

Under read. I.e. You will be going faster than the speedo says.

Changing your odometer or speedometer is not, in and of itself, an offence I believe.

Knowingly passing off a car as lower mileage than it actually is for financial gain would be, I believe. Doc can clarify with reference the relevant laws etc.

In other words, I can change my odometer to read whatever the hell I like with no penalty. But I am not allowed to then sell the car with a lower mileage than displayed without telling the prospective purchaser.

On a related note, conversely I believe it is illegal to have a speedometer under-read. It is allowed to over-read (ie tell you that you are going faster than you actually are), but not under-read.

In the circumstances suggested by OP, he would need to make some form of modification to his car to ensure his speedo is either 100% accurate, or over-reads within the allowed tolerance.

Last edited by choccymonster on 2nd Jan 2015 10:45 pm. Edited 1 time in total

Thehorse wrote:

Under read. I.e. You will be going faster than the speedo says.

Stick another needle on, or heat the existing one and bend it





I wasn't aware of the speed reading fact, difficult to see how or when that would be noticed

Keep up the mods ron, amazing what a transformation the cars under going, joking aside, replacing the speedo needle may be an option and a first?

ronp wrote:

Thehorse wrote:

Under read. I.e. You will be going faster than the speedo says.

Yep got that, it was the recording of mileage and the ave mpg.

@ choccymonster
Re the unlawful over reading of the speedo.
Wasn't aware of that.
How is this determined and by whom - is it an mot check?
Or is it a law that stands, but a vehicle isn't officially tested for?