Tyres - Swapping 21s for 19s

[DaveS]

Hi All,

This is going to seem like a silly question - but I want the 19" wheels, as I prefer comfort over style. I'm looking at used Enyaqs and the ones with the kit I want, all come with the 21" wheels.
I've asked the dealer if it is possible to swap the wheels over (not them doing it specifically - just if it can be done) and this was the reply:

"Unfortunately, you would not be able to swap out the 21’ for the 19’ alloys, as they are programmed to the car and would completely change the drive, it just isn’t something we can do I'm afraid."

In what way are the wheels programmed to the car? Is it to do with the inflation sensors? Is it true they can't be swapped at all?

[cailloux44]

I believe their answer is complete rubish...
I bought my Enyaq with 2 sets of wheels, both provided by Skoda on purchase. 20" with summer bands, 19" with winter bands.
Both drives like a charm, no configuration change required.
And I agree 19" is more comfortable. 20" is also quite OK to be honest.

[Dav00]

I think they can both be true? You can drive them like a charm, probably better than the 21, but something should be ideally reconfigured the get the most out of advanced management and monitoring? I wouldn't be surprised. Even consumption should be different, is the tyre size factored in by the system?

Also: I would check whether downsizing tyres would be considered by the insurance a modification. And should the tyre size be listed in the CoC? Are the 19 there?

[Martin26]

Isn't your distance of travel determined by the number of revolutions of your tyre? Or am I hopelessly out of date?

Going from 20" to 19" tyres would over report your mileage on your odomoter. (Smaller tyre, more revolutions to cover the same distance). If my maths is correct your mileage would show around 5% higher than the true mileage.

[Martin26]

Going from 21" to 19" would result in a 10% over state of your mileage.

[Powerstar]

I believe the tyre circumferences are virtually the same as the bigger diameter rims are fitted with lower profile tyres, one just ends up with a thinner tyre as the rim size increases

[CrowSysE243]

I believe the tyre circumferences are virtually the same as the bigger diameter rims are fitted with lower profile tyres, one just ends up with a thinner tyre as the rim size increases

I think that is correct. The reduced profile with larger wheels (nominally 55% of width for 19", 50% for 20" and 45% for 21") gives a nominal increase in overall diameter and rolling circumference of only about 0.5% going from 19" to 21" wheels for the 235mm tyres fitted on the 60 and the front of the 80, while tread wear results in a reduction of about 1.4% before the approaching the legal tread wear limit. For the 255mm tyres fitted on the rear of the 80s the nominal difference is less than 0.1%.

There is also variation between different tyre designs. The differences are small enough that the different wheel sizes can be used without the speed indication falling outside regulation limits.

235/55R19 has a nominal diameter of 741.1mm and circumference of 2328.2mm, reducing to a circumference of less than 2297mm before it reaches the legal wear limit.
235/50R20 has a nominal diameter of 743.0mm and circumference of 2334.2mm, reducing to a circumference of less than 2303mm before it reaches the legal wear limit.
235/45R21 has a nominal diameter of 744.9mm and circumference of 2340.2mm, reducing to a circumference of less than 2309mm before it reaches the legal wear limit.

255/50R19 has a nominal diameter of 737.6mm and circumference of 2317.2mm, reducing to a circumference of less than 2286mm before it reaches the legal wear limit.
255/45R20 has a nominal diameter of 737.5mm and circumference of 2316.9mm, reducing to a circumference of less than 2286mm before it reaches the legal wear limit.
255/40R21 has a nominal diameter of 737.4mm and circumference of 2316.6mm, reducing to a circumference of less than 2286mm before it reaches the legal wear limit.

[Aragorn]

My car came with 19's and i bought and fitted some 20s. Zero issues. And not a peep from Skoda about it when it was in for its Software update either...

Seems like nonsense from the Dealership to me.

As above the overall tyre circumference remains constant between the three wheel sizes.

I informed my insurer and they said as it was a factory option wheel there was no charge.

[C2atb]

The overall rolling radius should remain the same with the correct tyre size and can’t see why there would be a problem. Did you get any updates / responses