Handling experiment: 17"s vs 18"s

[Ess_Three]

Since the nice men at Audi damaged my 18" BBS rims, I had to remove them to have them re-furbished...and instead of fitting my spare set of 18" rims I decided to go back to the standarsd 17" set up to see how the fully sorted suspension set-up copes with 17" wheels and tyres.

I've been running this set up now for a few weeks...and it's not very nice!

My other half first commented that there was something wrong with the car...it just didn't feel right. Investigation was required...

She's right...
The set up I have was optimised for 18" lightweight (lighter than standard) wheels...and going back to heavier wheels with higher sidewall profiles has not improved the the driving experience one bit!

I tried my usual test roads...and have come to the following comclusions:
The car 'floats' on the standard wheels.
It turns in reasonably well...not as precise as on the 18s, but sharply...but it doesn't offer the same level of feedback as the 18s did. You seem to turn in, not instinctively know how much lock to apply, and have to wind corrective lock on or off to compensate - not ideal. It removes the fluidity of the previous set-up with the 18" wheels.

Once pitched into a set of bends at a decent pace, the car is not so predictable...it tends to wander off line, requiring continual small corrections.

I doubt this is down to rubber choice as I found the standard Bridgestones at least equal, if not better than, the 18" Avons.

Next step, tyre pressures:
I tried upping the front pressures, to remove some of the flex in the sidewalls...no good...too twitchy.
I tried upping the rear pressures to assist the precision of the turn in...better...but not sorted.
I tried lowering the rear pressures...horrible!

Several weeks later I have come to the conclusion that my previous combination is vastly better. I had perfect turn in, no float, no twitchieness and plenty of stability.
Although the overall grip levels are probably equal...we (g/f and I) appear more confident pushing a bit harder with the 18" wheels fitted.

So, now the 18" multi-piece wheels are repaired and re-bulit, I shall be re-fitting them with the minimum of delay. Great!

 

[chuckys3]

I've just moved from the standard 17" Avus S3 wheels which had michelins on them to 18" RS6 Goodyear's GSD3 wheels. The difference is unbelievable the traction is great. The handling is more sharper and the grip the car has now I can push it at higher speeds around bends and its an overall smoother ride.

 

[AndyMac]

I'd say it's probably more to do with the choice of rubber than the wheel size. I've had the unfortunate experience of Dunlop Sport (an oxymoron if ever there was one) tyres on my A3TS and changing these for P6000 completely transformed both the grip & handling. The bigger wheels will help, but without doing a wheel swap using the same tyres it would be difficult to say how much.

 

[Ess_Three]

I feel that the standard Bridgestone rubber is noticably grippier than the Avon rubbish on the 18"s.

In saying that...my other set of 18" BBS wheels had Pirreli P-Zero Neros on them...and they were abysmal...worse than the Avons even.
I have never driven on a Pirelli tyre yet that I've been happy on.

The floating I noticed is a function of the sidewall height...and the only way to erradicate that it so reduce it...ie, go up in wheels size, and go slightly wider on width (from a 7.5" to an 8") to tension the tyre somewhat.

There are noticable benefits of using the lighter wheels however:
The car changes direction quicker....the suspension has a much easier job to do giving a more complient ride, the car feels more lively when accelerating. All what you'd expect really.

There were other things to come out this little experiment:
I think you'd need more negative camber than I currently run to get the same front end grip on a 17" wheel and tyre combination.

It's far easier to set up the chassis by tweaking the tyre pressures on the 18" lower profiles.


What I was expecting was to find the car had slightly lower ultimate evels of grip, but with a more controlled break away happening at a lower point...this didn't seem to happen...the grip was similar but the whole 'feel' of the car different. Much nicer on the 18"s.
As you say Andy, a lot of that has to be down to the tyre compound / construction.

 

[RichA3Turbo]

[ QUOTE ]
Ess_Three said:
I have never driven on a Pirelli tyre yet that I've been happy on.


[/ QUOTE ]

Tried P-Zero Corsas?

 

[dunk]

i swapped from 17" avus with bridgestone s03 to 18" oem rstt with p zero nero,

with the 18" pirelli, i get lift-off oversteer (lots of fun in the dry but a but worrying in the wet, but its easily controllable) which i never got with the s03 rubber, and the overall feeling of confidence is way down compared to the s03 stuff

i think it is the rubber rather than anything else, but i plan to swap to gsd3 next or back to s03 on

my vote is the rubber not the wheels.

 

[Ess_Three]

[ QUOTE ]
RichA3Turbo said:
[ QUOTE ]
Ess_Three said:
I have never driven on a Pirelli tyre yet that I've been happy on.


[/ QUOTE ]

Tried P-Zero Corsas?



[/ QUOTE ]

No...and I'm not sure I would.

I think I'd go straight for the Japanese stuff which I know I can get on with..
Yoko 032s or 048s or similar.

 

[Ess_Three]

[ QUOTE ]
dunk said:

with the 18" pirelli, i get lift-off oversteer (lots of fun in the dry but a but worrying in the wet, but its easily controllable) which i never got with the s03 rubber, and the overall feeling of confidence is way down compared to the s03 stuff


[/ QUOTE ]

I hate Pirellis...I just can't get on with them!


[ QUOTE ]

i think it is the rubber rather than anything else, but i plan to swap to gsd3 next or back to s03 on
my vote is the rubber not the wheels.


[/ QUOTE ]

I'll concede that the grip is down to the rubber...overall there's nothing in it, 18" Avon vs 17" Bridgestone... so logically going to a batter 18" tyre would yield another advantage.

The handling position is different though...floating from sidewall height, wheel weight and tyre weight are different again.
(BTW my Pirelli 18" tyres weigh 1lb more than my Avons)
The degradation is chassis feel, flickability, suspension composure is a function of fitting the heavier 17" wheels over lightweight 18" wheels.

Anyone with expensive lightweight 18" wheels will be onto a winner...the weight lost there is a huge advantage to the handling!

 

[pure]

Glen, what is the weight difference on your BBS wheels compared to the other 18"'s and the 17"'s you have?

 

[neil.c]

Swaping from 205/50 15's to 215/40 16's on the wife's golf Gti 16v I noticed similar things, the car turned in much quicker there was less float on uneven roads and you did not have to wait for the mass of the car to load the sidewall of the tyre when altering direction, but the ride was less compliant.

 

[Khufu]

I came from standard 195/65 R15s with Dunlop fuel saving tyres to 225/45 R17s with Mitchelin Pilot Sports on my A3 - enough said /ubbthreads/images/graemlins/laugh_roll.gif

 

[chuckys3]

If anyone is looking for tyres. I found this great website and the price for tyres is great too .. better then kwick fit anyday /ubbthreads/images/graemlins/smile.gif
http://www.mytyres.co.uk/start.html
the website is great and you should check out there prices..

 

[ANDYTQ]

I swapped from mich pilots to goodyear f1's on my ibiza cupra,the difference was like night and day,much more grip and feel ,wet or dry.Cheers Andy

 

[Sam_]

Just an 8 year bump here.

Are 18s really better for handling or is it as above, more about the tyres?

I've been offered some 17x9s and provided they fit over my brakes, I might take them. I was thinking of running 245/40/17s if I can get them in. Would this be worse than an 18x8.5" running 225/40s ?

 

[cecilthesausage]

 

[Prawn]

Personally, I've always found the chassis handles better on 17's rather than 18's, the ride on 18's is horrible, 17's just feel nicer. You do get a bit more sidewall movement, but that doesn't seem to be an issue to me.

Several people have all commented that their cars feel better on 17's than 18's.

I think the difference Glen noticed above was more down to wheel weight than size, he was replcing lightweight 18's for heavy 17's.

Given equal weights, I'd go 17's every time.

 

[Sam_]

The new wheels are actually 1.7kg lighter than current so shouldn't be a problem?

 

[jojo]

I can tell you that my car handles better on 18s than it does on 19s. I did run standard 17s on my previous S3 for a while, but never really pushed the limit of the car. I did feel it wasn't as good as 18s though.

 

[Sam_]

I wonder if it's also a width and tyre choice (sidewall rigidity) thing...

 

[JohnM100]

The original post was from 2004.

Can't comment on the GoodYear F1s but the Michelin Pilot Sports have come a long way in that time. The PS3s are a world better than the PS2s which were only marginally better than the originals with the old style herringbone pattern.

I prefer 17s to 18s as the sport suspension is pretty firm anyway and the extra height of the sidewall on the 17inch helps soften those ruts in the tarmac and road noise.

John.

 

[Westy]

I've don't track days on 17s and 18s and I've found the 17s offer more control.

 

[kwistof]

I went from 17s to 18s last year after having the 17s for 3 years.

Personally I would say the handling was slightly better with the 17s - both were fitted with the same brand and tyre model. (Michelin PS3's).