20” v 21” wheels - overall size difference?

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ecmacan
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Joined: Sat Feb 01, 2020 10:09 pm

20” v 21” wheels - overall size difference?

Post by ecmacan » Fri Feb 14, 2020 12:31 pm

Hi folks,

Just wondering is there a substantial difference in the total wheel size (rim + tyre walls) between 20” and 21” options? (Assuming both are running on summer tyres). From the configurator, it seems as though the ‘arch fill’ is the same but could anyone confirm this please?


As for the width, I believe the rear is the same whereas the front is slightly larger on 21 inchers?


Thanks


pmg
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Re: 20” v 21” wheels - overall size difference?

Post by pmg » Fri Feb 14, 2020 12:50 pm

ecmacan wrote:
Fri Feb 14, 2020 12:31 pm
Hi folks,

Just wondering is there a substantial difference in the total wheel size (rim + tyre walls) between 20” and 21” options? (Assuming both are running on summer tyres). From the configurator, it seems as though the ‘arch fill’ is the same but could anyone confirm this please?


As for the width, I believe the rear is the same whereas the front is slightly larger on 21 inchers?


Thanks
Should be no difference in the total combined wheel and tyre size between the 4 rim sizes

All the info I have seen shows the same width sizes between 18's and 19 's and then between the 20's and 21's with the latter two being wider. greater width has advantages in dry conditions but disadvantages in the wet or in snow. For that reason 18's and 19 rims make more sense for separate winter wheels set than 20's and probably the reason Porsche do not approve winter 21" tyres.

1. (front) 235/60R18
(rear) 255/55R18
2. (front) 235/55R19
(rear) 255/50R19
3. (front) 265/45R20
(rear) 295/40R20
4. (front) 265/40R21
(rear) 295/35R21
2019 Macan S Porsche code PKW8WKI8


putt4par
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Re: 20” v 21” wheels - overall size difference?

Post by putt4par » Fri Feb 14, 2020 1:00 pm

Yes both 20 inch and 21 inch rims are 9J on the front and 10J on the back.

The 21`s would give the appearance of filling the arch more as there in more wheel and less rubber but as previously indicated both sizes have very similar rolling radius.


ecmacan
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Joined: Sat Feb 01, 2020 10:09 pm

Re: 20” v 21” wheels - overall size difference?

Post by ecmacan » Fri Feb 14, 2020 1:13 pm

Thank you gents


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Guy
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Re: 20” v 21” wheels - overall size difference?

Post by Guy » Fri Feb 14, 2020 1:49 pm

By my maths, the 20 inch combination is bigger front and rear!

(Edited to include 18 and 19 inch)

Untitled.png



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ScotMac
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Location: Scotland

Re: 20” v 21” wheels - overall size difference?

Post by ScotMac » Fri Feb 14, 2020 2:27 pm

That is interesting.

I thought that all wheel sizes were roughly the same.


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Rab J
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Re: 20” v 21” wheels - overall size difference?

Post by Rab J » Fri Feb 14, 2020 2:43 pm

The difference is 0.15% between 20" and 21" front so the square route of nothing. Its almost impossible for two different tyre sizes to have exactly the same rolling radius.
Macan GTS Carmine with 21" black sports classics ---Gone
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bennachie
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Re: 20” v 21” wheels - overall size difference?

Post by bennachie » Fri Feb 14, 2020 4:10 pm

Gnats whiskers of a difference. The difference between a new and a worn tyre.........
'The secret of life is enjoying the passage of time'


pmg
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Re: 20” v 21” wheels - overall size difference?

Post by pmg » Fri Feb 14, 2020 4:35 pm

bennachie wrote:
Fri Feb 14, 2020 4:10 pm
Gnats whiskers of a difference. The difference between a new and a worn tyre.........
and production tolerances on tyres? The maths above depends on very much on the profile being absolutely accurate
2019 Macan S Porsche code PKW8WKI8


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PaulR
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Re: 20” v 21” wheels - overall size difference?

Post by PaulR » Fri Feb 14, 2020 7:49 pm

As Guy points out, there's very little difference between the 20" and 21" wheels. Many people say the 21" wheel fills the wheel arch better, but they're talking rubbish. The reality is that the 20" wheel is the overall biggest size - by a whisker. But - because you have a slightly larger tyre wall - you get much better comfort levels. And, in the case of the GTS, better handling characteristics.

Everyone will argue with me, however that's because everyone wants the 21" wheels to be better. My experience in test driving various models is that the 20" ones give the best performance. Especially in the GTS model which, because it's lowered, exacerbates handling problems in the 21" wheel size (versus the other models where less of an issue).

If you go for a black wheel, then I've found the wheel and tyre effectively merge into each other. So the overall look is the same. Unless you go the Sport Classic wheels which, due to the diamond-cut rim, help highlight the larger wheel size.
Gone - 2018 Macan GTS
Imminent - 2020 Macan GTS


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