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I currently have the new shape focus on an '11' plate... Its the titanium x model that comes with the 18" alloys with Michellin Pilot Sport 3's 235/40 ZR18 as standard... I already owned a set of winter tyres which I used to put on my old car but this car had the 16" alloys on. So I have purchased 16" [url=""][color="#545454"]steel wheels[/color][/url] and had the Michellin Alpin A4's 205/55 R16 fitted to them.
I've now swapped my wheels over and thought all was good until I called into my local ford dealer today when he told me I may well of now invalidated parts of my warranty by swapping to smaller wheels but also that i've possibly caused lots of problems now and that i should have the car reprogrammed with the wheels set at this new diameter and at a cost of around £50 !!!!!! As the speedo, abs, trac control etc all work off the wheel size....
Is this correct or am I been fed a bit of nonsense???


[i]what a load of bull. i have never heard of this before. the rolling radius is probably the same. i'm sure there is a way of calculating this or a website that shows the difference.[/i]
Speedo is about 10% off anyway, you cant not have warranty because you changed the wheels, i would take his name, then send Ford an email to there customer services. See what they say....When i did this my local dealership started to do their jobs properly!
Mr Singh
the dealer is correct in saying that the wheels will 'need programming to the car' but invalidating the warranty is bull!
Speedo works off the rolling radius of the TYRE, not the wheel.

Yes your winter tyres are on a smaller wheel, but the important fact is that the sidewall profile is larger to compensate for this.

The actual rolling radius of the tyre is only 2% different, which is absolutely fine and well within normal limits.

I checked on a tyre comparison website:

Your standard wheel/tyre has a total diameter of 645mm
Your winter wheel/tyre has a total diameter of 632mm
The difference in total diameter is 13mm

That's the difference between a new tyre and a worn-out tyre
(New tyre has 8mm tread, legal limit is 1.6mm, so you lose 6.4mm per side. Total loss of diameter is 6.4 x 2 = 12.8mm)

It's just maths.

Is the dealer suggesting that you have your speedo calibrated as your tyres wear out? And then again as you buy a new set?

And what warranty parts could possibly be invalidated? If anything, your winter tyres will have better ride comfort because of the deeper sidewalls, and that will mean less shocks through the suspension etc.
Try going over a pothole on each set of tyres...

He's yanking your chain.
cheers pitmonster great reply... all he asked when he saw i didnt have the 18 alloys on was had i had the car reprogrammed so it knew it had different size wheels on... threw me a bit to be honest as it did puzzle me a tad... he just said it needed doing or else i had the chance of errors popping up to do with speedo/abs etc.....
but driving the car tonight i had my tomtom on and on cruise control the speed on the satnav was within 3 or 4 mph of what the speedo was reading...
He was angling for work.
They'd likely put the car in the bay for two hours while they go for a fag break and an extended lunch, return it to you and charge you for the honour.
Was he wearing a striped jumper and a black mask?
You're very welcome :-)
Or is it the rumour that ford calibrated the ecu to show better mpg than what youre really getting my uncles 12plate was recalibrated and doing brim tests the trip says 46mpg the brim test shows 41mpg thats 5different brim tests and each time the trip is stating more it may be paranoia but there are rumours of this fords excuse is the computer wasnt calibrated to the correct size of tyre
[quote name='Stoney871' timestamp='1354224938' post='219023']
He was angling for work.
They'd likely put the car in the bay for two hours while they go for a fag break and an extended lunch, return it to you and charge you for the honour.
Was he wearing a striped jumper and a black mask?

Or was he riding around on a horse
A not so dandy highwayman.
A Dick Turpin without the Turpin. ;)

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