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Discussion Starter · #1 ·
Hey gang,

I've ordered a set of 20" already; waiting for them to arrive, but last night I was given a ride in my friend's RS4 on 20" HREs, and my god, it felt horrible...it felt like I was riding on rails. Granted where I live (San Francisco) the roads aren't the most ideal, but compared to my stock 19s, it was a pretty harsh ride.

I am 2nd guessing my order...might consider re-selling them when they arrive and downsize to 19s.

Anyone on 20s have ride / comfort input? Much appreciated, thanks!
 

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What were the specs on his tires? That's the important part, not the size of his wheels.......:cool:
 

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What about 265/30/20?

I believe I read somewhere that the 9 x 20" RS4 style wheels available as an option for the A5 in Germany come with 265/30/20 tires (not sure which brand). The only problem is there don't seem to be too many tire manufacturers that make that size tire. Continental and Michelin are the two that come to mind, but the Michelin's are around $500 per tire in that size. Conti's are half that price.

I'm guessing that size tire might provide more comfort.
 

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No they won't. If you have 20" wheels and maintain the correct rolling diameter ( which you need to do for speedo accuracy, suspension geometry etc ) then the radial thickness of rubber ( which essentially provides the cussioning ) will be the same ( hence the change in aspect ratio numbers as you go up in tyre width ) So whichever way you look at the ride will be fairly badly compromised on 20" wheels. 19" wheels, Suspension lowering and spacers is the way to go.
 

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Discussion Starter · #6 ·
What about 265/30/20?
I don't think the width of the tire would improve comfort / ride-ability...but someone correct me if I'm wrong.
 

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Discussion Starter · #7 ·
But I do have to say the look of 20s on our car is just so proportionally meant to be...

I guess I can roll on the 20s for a bit, see how I like them, then sell them later if I don't like the ride comfort...

Is Quattrings the only guy with 20s on an S5?
 

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But I do have to say the look of 20s on our car is just so proportionally meant to be...

I guess I can roll on the 20s for a bit, see how I like them, then sell them later if I don't like the ride comfort...

Is Quattrings the only guy with 20s on an S5?
When you've sold them, you can use the money to pay the dentist to put your fillings back in!
 

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I don't think the width of the tire would improve comfort / ride-ability...but someone correct me if I'm wrong.
'
Actually, you are slightly wrong!

The XXX/30 is an 'aspect ratio' being 30% of the width of the tyre, therefore a 295/30 will have a larger tyre wall (88.5mm) than 255/30 (76.5mm).

However, as graham points out as the rim diameter increases, you need to decrease the profile of the tyre to maintain the rolling radius.

30 or less is harsh as hell and is also noisier because there is less tyre wall to 'flex' which provides cushioning and isolation from road noise.

Ian.
 

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No they won't. If you have 20" wheels and maintain the correct rolling diameter ( which you need to do for speedo accuracy, suspension geometry etc ) then the radial thickness of rubber ( which essentially provides the cussioning ) will be the same ( hence the change in aspect ratio numbers as you go up in tyre width ) So whichever way you look at the ride will be fairly badly compromised on 20" wheels. 19" wheels, Suspension lowering and spacers is the way to go.
Sorry, but this is so wrong.

If I ride on a 285/25 tire I have less than 3 inches of sidewall which makes for a horrible ride. If I go for a 265/30, the sidewall is a fraction less than the stock 255/35 tire that everyone is comfortable with. Nothing has been compromised at all.

The size of the wheel does not compromise the ride if you understand the correct tire size and wheel widths to purchase.....
 

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Sorry, but this is so wrong.

If I ride on a 285/25 tire I have less than 3 inches of sidewall which makes for a horrible ride. If I go for a 265/30, the sidewall is a fraction less than the stock 255/35 tire that everyone is comfortable with. Nothing has been compromised at all.

The size of the wheel does not compromise the ride if you understand the correct tire size and wheel widths to purchase.....
'
...Actually Graham is right... what is not clear from what he wrote was that if you increase the wheel diameter, you should decrease the profile (ergo - wall height) to maintain the correct rolling diameter... this WILL compromise ride quality... However, in the example you quote sizzle you have an 11% reduction in wall height (10mm), and a 2% increase in circumference, which WILL decrease the ride quality and throw your speedo and gearing out by 2% (which is neither here nor there)... Heres the math:

19" with 255/35:
wall profile = 89.25mm
Rolling Diameter = 661.1
Circumference = 2075

20" with 265/30:
wall profile = 79.5mm
Rolling Diameter = 649
Circumference = 2037

Ian.
 

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'
...Actually Graham is right... what is not clear from what he wrote was that if you increase the wheel diameter, you should decrease the profile (ergo - wall height) to maintain the correct rolling diameter... this WILL compromise ride quality...
I don't deny that there will be a decrease. My point is that the ride will not be compromised to the point that you need to "get new fillings." There will be a very minute difference in ride quality with the right size tire and wheel specs. A 10mm difference in sidewall height is nothing and I speak from extensve experience plus sizing wheels and tires.
To act like a 20" wheel automatically gives you a bone jarring ride is simply incorrect.


However, in the example you quote sizzle you have an 11% reduction in wall height (10mm), and a 2% increase in circumference, which WILL decrease the ride quality and throw your speedo and gearing out by 2% (which is neither here nor there)...
Which is exactly my point. If someone were to say, a 20" wheel "throws your speedo out of whack" that would be incorrect as well. There is a difference yes, but it will be very minute just as the ride quality will be with this tire size. Here are the actuals regarding both tire sizes. They are a bit less dramatic than what you cited:

255/35R19
265/30R20

Section Width: 10.03 in 255 mm
Section Width: 10.43 in 265 mm

Rim Diameter: 19 in 482.6 mm
Rim Diameter: 20 in 508 mm

Rim Width Range: 9.5 - 10 in
Rim Width Range: 9 - 10 in

Overall Diameter: 26.02 in 660.90 mm
Overall Diameter: 26.25 in 666.75 mm

Sidewall Height: 3.51 in 89.154 mm
Sidewall Height: 3.12 in 79.248 mm

Radius: 13.01 in 330.45 mm
Radius: 13.12 in 333.24 mm

Circumference: 81.74 in 2076.1 mm
Circumference: 82.46 in 2094.4 mm

Revs per Mile: 799.3
Revs per Mile: 792.3

Actual Speed: 60 mph 100 km/h
Speedometer1: 59.4 mph 99.1 km/h

Speedometer Difference: - Speedometer Difference: 0.883% too slow
Diameter Difference: - Diameter Difference: 0.88%
 

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We be in violent agreement...

...I said nothing about being too hard... just harder.

and yes, I just checked my maths and I have the diameter of the 20 wrong. Doh!...

Now we get into the territory of 'sulcated' spring design and maths... 11% change in wall height... approximates to 22% stiffer side wall! All things being equal... which they're not quite... and so on... ad infinitum!
 

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Hey gang,

I've ordered a set of 20" already; waiting for them to arrive, but last night I was given a ride in my friend's RS4 on 20" HREs, and my god, it felt horrible...it felt like I was riding on rails. Granted where I live (San Francisco) the roads aren't the most ideal, but compared to my stock 19s, it was a pretty harsh ride.

I am 2nd guessing my order...might consider re-selling them when they arrive and downsize to 19s.

Anyone on 20s have ride / comfort input? Much appreciated, thanks!
'
Don't forget that's the RS4... which also has much stiffer suspension than the S5... that is probably the biggest difference in ride quality.
:)
 

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So, what are the WIDEST tyres you can fit on the S5?

TX, can the S5 actually fit 265's without rubbing?
 

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TX, can the S5 actually fit 265's without rubbing?
Rab, I can't say for sure what the widest tire is without rubbing issues. All I know is that I recall reading (on a German forum I think) not too long ago that someone's optional 9 x 20" RS4-style wheels came with 265/30/20 tires from the Audi factory. I think it's safe to assume that there would not be any rubbing issues with that setup anyway.
 

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Hey gang,

I've ordered a set of 20" already; waiting for them to arrive, but last night I was given a ride in my friend's RS4 on 20" HREs, and my god, it felt horrible...it felt like I was riding on rails. Granted where I live (San Francisco) the roads aren't the most ideal, but compared to my stock 19s, it was a pretty harsh ride.

I am 2nd guessing my order...might consider re-selling them when they arrive and downsize to 19s.

Anyone on 20s have ride / comfort input? Much appreciated, thanks!
You could choose a larger profile (side wall) size and then lower the car to maintain the same height, this would then reduce the effect of the bigger wheels more. Not sure how this would effect the speedo reading though.
 

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largest? I've see cars from the 'tuning' (yeah right!) houses with 295 on the rear and 265 on the front.

...as for a larger wheel with a large side-wall... this will affect the speedo and the gearing... bear in mind that more than 7% difference is not only inadvisable, but ILLEGAL in the UK as you car would fail an MOT for having no effective speedometer.
 
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