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225 Tyre vs 205 Tyre
#1548399
04/09/2015 00:47
04/09/2015 00:47
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Joined: Apr 2015
Posts: 575 Ayrshire
ScouseCoupe
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I've read that with the standard 16" alloy wheels for the 20VT, that 2 sizes of tyre can be fitted, either a 205/50 ZR16 or 225/45 ZR16.
In the real world, are their any other benefits in having a wider track tyre, other than a harsher ride with a 45 profile against a 50 profile tyre.
My rears being Conti Sport Contac 3's that are past their best at 2.5mm - 3mm tread left ( 205/50/16 91Y ), further the fronts being Falken Ziex ZE-912 ( 205/50/16 87V ) that I really do not like. Whatever I decide for the rear in tyre sizes will determine the front as well, which may determine the fate of the horrid Falkens.
Opinions / Advice please. Thanks.
1999 Rosso Corsa 20VT ( Restored ) 2000 Rosso Alfa 916 Spider 2.0 T.S Lusso ( Under Restoration)
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1548400
04/09/2015 00:55
04/09/2015 00:55
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GrahamL
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GrahamL
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It doesn't make much, if any difference.
The side walls are almost the same, 102.5mm (205*0.50) v's 101.25mm (225*0.45) so there's no difference in ride quality.
There's much more difference between different types of tyre in the same size than between the same tyre in those 2 different sizes.
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Re: 225 Tyre vs 205 Tyre
[Re: ]
#1548401
04/09/2015 01:03
04/09/2015 01:03
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Joined: Apr 2015
Posts: 575 Ayrshire
ScouseCoupe
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It doesn't make much, if any difference.
The side walls are almost the same, 102.5mm (205*0.50) v's 101.25mm (225*0.45) so there's no difference in ride quality.
There's much more difference between different types of tyre in the same size than between the same tyre in those 2 different sizes. Thanks Graham, so in reality stick to the size that's already fitted...but choose wisely on the brand / type of tyre.
1999 Rosso Corsa 20VT ( Restored ) 2000 Rosso Alfa 916 Spider 2.0 T.S Lusso ( Under Restoration)
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1548403
04/09/2015 01:12
04/09/2015 01:12
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GrahamL
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GrahamL
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Fiat switched to the wider tyre size in late '99 so the 225/45 and the earlier 205/50 size are both considered standard fit.
Some tyres are only available in one of those sizes so I'd pick based on tyre make, model (performance) and price, rather than specifically which size.
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1549518
15/09/2015 13:50
15/09/2015 13:50
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Joined: Apr 2015
Posts: 575 Ayrshire
ScouseCoupe
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Are you allowed to run 225 on rear and 205 on front, till the fronts are worn out and change them to 225 ?
1999 Rosso Corsa 20VT ( Restored ) 2000 Rosso Alfa 916 Spider 2.0 T.S Lusso ( Under Restoration)
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1549525
15/09/2015 14:50
15/09/2015 14:50
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Joined: Dec 2005
Posts: 1,302 Pontefract, West Yorkshire
andyps
Club member 1482
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Club member 1482
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Are you allowed to run 225 on rear and 205 on front, till the fronts are worn out and change them to 225 ? No reason why not as far as I know, it is what I have on mine at the moment.
Andy
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1549533
15/09/2015 17:02
15/09/2015 17:02
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Joined: Dec 2005
Posts: 17,367 Staffordshire
Nigel
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Are you allowed to run 225 on rear and 205 on front, till the fronts are worn out and change them to 225 ? Yes, but be careful with the differences in grip at one end (caused by the difference in tyre make, NOT the difference in tyre size)
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1549551
15/09/2015 21:56
15/09/2015 21:56
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Joined: Dec 2014
Posts: 420 uk
OnlyItalian
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Narrower tyre would mean more sidewall strength as the rim helps support it more. So the steering will feel more direct and responsive with the narrower tyre.
"Proud owner of LE141 and a 99 VIS broomie "
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Re: 225 Tyre vs 205 Tyre
[Re: andyps]
#1549813
18/09/2015 00:03
18/09/2015 00:03
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Lego
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Lego
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Pretty sure Audi fitted the last generation RS3 with wider tyres on the front than the rear
Yes you are right. Wider tyres on front.
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Re: 225 Tyre vs 205 Tyre
[Re: ]
#1549826
18/09/2015 02:29
18/09/2015 02:29
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Joined: Dec 2005
Posts: 3,694 Midlands
MCMike
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never heard of this before !
1972 Triumph Stag 1984 Alfasud TI 1999 Fiat Coupe Turbo LE 2005 350Z
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1549895
18/09/2015 15:47
18/09/2015 15:47
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Joined: Oct 2010
Posts: 555 Bulgaria
Ferrarist
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In the real world, are their any other benefits in having a wider track tyre, other than a harsher ride with a 45 profile against a 50 profile tyre.
IMHO wider tires gives more grip, no matter what that so often quoted equation about pressure over contact patch said. Tires provides mechanical grip, and more patch on the road always mean more grip. However here is different view of this - AutoSpeed link. There was few tests available from tyre makers proved that that article is not true, Avon was one of the makers.....It's different story that wider tires matters when you stopping, accelerating, and cornering - and there is "weight transfer".....which pushes every corner or side of the car on it's tires.....and this "push" provides more grip from the tires....wider tire provide logically more grip...... However there is downsides as well - less MPG, more power waste, and sometimes bigger or upgraded brake system......because more grip from tires always mean more heat during extreme stops.....and so on..... It's my opinion only......
Last edited by Ferrarist; 18/09/2015 15:49.
20VT - Alfa 156 2.0 - Alfa 156 Mid-Engined RWD - Locost 20VT
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Re: 225 Tyre vs 205 Tyre
[Re: Ferrarist]
#1549951
18/09/2015 22:12
18/09/2015 22:12
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Joined: Dec 2005
Posts: 17,367 Staffordshire
Nigel
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IMHO wider tires gives more grip, no matter what that so often quoted equation about pressure over contact patch said. Tires provides mechanical grip, and more patch on the road always mean more grip. No, no, no - wider tyres cannot provide MORE grip - its a physical impossibility - they will provide DIFFERENT grip, but not more. For the same tyre, there is only one way to provide more grip, and that is more weight. The only way to provide more weight is with downforce, which the Coupe simply can't give (at least not without some VERY serious mods) If you increase the width of the tyre, the car still weighs the same, so the contact patch will be a different shape, but NOT a different area. Therefore the characteristics of the grip (lateral, longitudinal, slip-angle etc) will change when the contact patch shape changes, but the overall level of grip will remain constant. If you lower the tyre pressures, the contact patch area will increase, but the weight of the car will remain the same, so the weight is simply spread over a larger area and the overall grip will remain the same I accept that you can increase grip by changing tyre compound, but that's not what we're on about here
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1549997
19/09/2015 09:15
19/09/2015 09:15
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Joined: Oct 2010
Posts: 555 Bulgaria
Ferrarist
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Enjoying the ride
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Bulgaria
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If stationary,a Coupe front axle wheels supports 750kg weight, about 450 rear axle...... When braking hard did front axle still supports 750kg? If not, is that more weight "shifted" from one end to other?
20VT - Alfa 156 2.0 - Alfa 156 Mid-Engined RWD - Locost 20VT
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1550021
19/09/2015 18:32
19/09/2015 18:32
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Joined: Apr 2015
Posts: 575 Ayrshire
ScouseCoupe
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I've decided to stick with the 205's at the rear, like they are on the front and keep things standard as it is. All i need to do is shortlist some tyre brands / specs to suit the driving conditions that i will use the Coupe for.
1999 Rosso Corsa 20VT ( Restored ) 2000 Rosso Alfa 916 Spider 2.0 T.S Lusso ( Under Restoration)
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Re: 225 Tyre vs 205 Tyre
[Re: Nigel]
#1550069
20/09/2015 00:45
20/09/2015 00:45
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Joined: Oct 2010
Posts: 555 Bulgaria
Ferrarist
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With weight transfer, the extra grip experienced by one pair of tyres (whether front to rear, or side to side), is proportionately reduced on the other pair, so overall grip remains the same
If we assume that this is correct, why not wider tires provide more grip? So - a stationary Coupe has the same overall grip as one that's moving and hard on the brakes Newton's laws stops as soon as the car moves. Here is short quote form "Tune to win" Book by Carroll Smith, a very useful and understandable source: The racing tire does not follow Newton's Laws of Friction - which are for friction between smooth bodies. It can, and does, generate forces greater than the loads applied to it. Further it can develop an accelerative force, a decelerative force, side force or a combination of either an accelerative force and side force, or a decelerative force and side force. In case of combined lateral and longitudinal forces, the sum can be considerably greater than the maximum force that can be developed in any one direction.Here is interesting page shot: It does not said "wider is better", but for me its more than obvious....and there is no point for me to give any more arguments, below is the link where anybody can download WORD format of this book, and if have free time - to make his own conclusion. Tune to Win
20VT - Alfa 156 2.0 - Alfa 156 Mid-Engined RWD - Locost 20VT
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Re: 225 Tyre vs 205 Tyre
[Re: Ferrarist]
#1550075
20/09/2015 02:24
20/09/2015 02:24
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Joined: Dec 2014
Posts: 420 uk
OnlyItalian
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Here is short quote form "Tune to win" Book by Carroll Smith...
Further it can develop an accelerative force, a decelerative force, side force or a combination of either an accelerative force and side force, or a decelerative force and side force.
I've got a copy of that book. IIRC he refers to this as the traction circle.
"Proud owner of LE141 and a 99 VIS broomie "
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Re: 225 Tyre vs 205 Tyre
[Re: Ferrarist]
#1550178
21/09/2015 11:56
21/09/2015 11:56
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Joined: Dec 2005
Posts: 17,367 Staffordshire
Nigel
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Forum veteran
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Newton's laws stops as soon as the car moves. Newton's law cannot simply cease to apply simply because the car is moving.... The quote above that Newton's law applies only to smooth bodies is simply wrong - Newton's laws apply to any body Also, to state "it can and does generate forces greater than the loads applied to it" is questioning Newton. I know modern tyres are good, but I rather doubt they have invented a way to overcome physics. In any event, all of the above is off-topic - we're not talking about friction specifically, we're asking whether friction (grip) increases if you increase a tyre's width. Until you can prove that the pressure/area calculation doesn't work, then it still applies and therefore a wider tyre CAN'T offer any more grip
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1550184
21/09/2015 12:54
21/09/2015 12:54
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Joined: Aug 2013
Posts: 382 UK
Downhillryder
Making a profit
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Making a profit
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According to THIS debate on Physics Stack Exchange wider tyres can offer more grip on cornering because of the contact patch and slip angle. Anyhow see link for more, including points already made in the thread.
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Re: 225 Tyre vs 205 Tyre
[Re: ScouseCoupe]
#1550268
21/09/2015 21:15
21/09/2015 21:15
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GrahamL
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GrahamL
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The wider tyre has less of it's circumference in ground contact during each rotation, so the rubber runs cooler and can therefore be run faster. AIUI that's the main reason that F1 tyres are so wide.
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