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 Post subject: The performance gains / losses from 17" Wheels?
PostPosted: Sun Oct 31, 2004 9:38 pm 
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Joined: Tue Oct 05, 2004 8:21 pm
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17" alloys would enhance the styling of the car. But would they mess up the fantastic handling?
Also, would the increased circumference of the wheels render the speedo innacurate?
Would the increased circumference mean a higher top speed or quicker acceleration?


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 Post subject:
PostPosted: Sun Oct 31, 2004 11:29 pm 
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Joined: Mon Oct 11, 2004 11:18 pm
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Location: Somerset, UK
Are you telling me, that you don't know the answers to such basic motoring questions, sunshine ? Jeez ...
(Strange that, because I thought you knew 'everything', including my life history.......(NOT !).......)

Anyway, let me help you, though God only knows why I should.

17" alloys will look great, but will probably be heavier and therefore will affect the handling, to some degree. We owners know that the ride is pretty solid already and going down to 40-series tyres from the stock 55-series, (to keep the gearing close to standard) will probably make the ride intolerable, due to the lack of cushioning effect a higher sidewall on the tyre gives.

The speedo. would only be affected if you don't keep the gearing standard or near-standard, by using 40-series tyres. If you do increase the circumference, then the speedo will under-read and the car will have a higher theoretical top speed and suffer a loss of acceleration.
It is a more complicated subject than that, though, with aerodynamics coming into it, because the car may not pull the higher top gear anyway, so a raise in gearing may be a loser all-round.......

My overall advice, is that you should keep the stock wheels and give them a different finish, if you want to. The stock wheels are narrow and have little frictional losses. Bigger and wider wheels will make the car slower because of the increased drag and weight.

Glad to be of use to you.
Now show some respect, PatriotUK.......


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 Post subject:
PostPosted: Mon Nov 01, 2004 7:26 am 
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So if I keep the gearing standard:
The car will be faster
The speedo will under-read
This means if the speedo says 40mph, I could be doing say 44mph, setting off speed cameras?


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 Post subject:
PostPosted: Mon Nov 01, 2004 9:45 am 
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Location: Somerset, UK
Hold on a second...

If you go to 17" wheels, you will have to fit 205/40 tyres, which have a similar rolling circumference to the stock 185/55 x 15. So the speedo. will read almost the same. The car will accelerate the same and have the same top speed, give or take 1% or so. From a point of view of the gearing that is.

However, the car will look better perhaps. The trouble being, the wider and heavier wheel will slow the car, via increased weight and drag. I have spurned the offer of some 17" wheels, since I prefer the light weight and low drag of the stock wheels, which I am finishing in flat black when I get time. Also, wider wheels may be worse in the wet due to the decreased weight over each inch of tyre.
The Ignis Sport was set up to have 15s and my view is that they are best for the light weight and low power output.


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 Post subject:
PostPosted: Tue Nov 02, 2004 3:27 am 
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Location: Netherlands
I Don`t think that the wheels would be more weight.
I have done some research and i found out the the 17 inch will be less weight than the 16 inch , so i think that the 15 will be heavier than the 16 inch, because of the % of aluminium against rubber.
you will find this at this page

http://babelfish.altavista.com/babelfis ... index.html

I personally think that the grip you have by pulling away be better, sometimes when i pull away my front tires spin..

i will putt 17 inch under my car..


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 Post subject:
PostPosted: Tue Nov 02, 2004 3:36 am 
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Location: Somerset, UK
I really would NOT go with the thinking that bigger wheels will thus be lighter !
It MAY be the case, in odd circustances, but is rarely so.

You would also have to fit a wider tyre, which is going to slow the car, remember, via increased drag. I have never heard of 185/40 x 17 and doubt that tyre exists. 205/40 would be the tyre to use with a 17" rim.

Caterham use very small wheels on their top models, because smaller rims are inevitably lighter and have a smaller contact patch for least resistence. Light cars do not need huge wheels.

The Ignis will perform best on 15" wheels but I agree the 17s will look better.


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 Post subject:
PostPosted: Tue Nov 02, 2004 5:04 am 
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i somecase you have right, but do you also agree with me that the standard tires at our car does not have much grip when pulling away.
At a rainy day the tires whe have are to bad. lasttime i pulled away and for a second or 3 al the thing i did was spinning. Hate that . And i was not pulling fast away..


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 Post subject:
PostPosted: Tue Nov 02, 2004 5:10 am 
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Location: Somerset, UK
Wider tyres will often be WORSE in the wet though !
This is because the grip offered will lessen as the weight over the contact patch reduces.
People who fit huge tyres to cars often find that they are a nightmare in the wet for this reason.

To be honest, the car will not be drastically different in any direction after the wheel swap you have planned, but big wheels like everything else in life and motoring, are a compromise.


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 Post subject:
PostPosted: Wed Nov 03, 2004 2:49 am 
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But i think that the grip in the summer time will be better, and i agree with you that when it`s rainy the grip will me bad.. Last month i spoke a guy who had 17 inches under his ignis , he said that ride handeling was improved. I will discover it by myself when i have 17 inches under my car.


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 Post subject:
PostPosted: Wed Nov 03, 2004 3:28 am 
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Fair enough. Have fun.


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 Post subject:
PostPosted: Wed Nov 03, 2004 7:41 am 
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I will tell you if 17 inches under a ignis will improve or disimprove handeling. butt that will be about a month or 6 because winter is coming and now i don`t putt new alloys wheels under my car..


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 Post subject:
PostPosted: Sat Nov 06, 2004 8:13 am 
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Great, let us know how it goes. Saw one on factory 16s today.


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 Post subject:
PostPosted: Sat Dec 11, 2004 9:15 am 
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porsche man, i'm wondering if you've ever had wider and lower profile tyres on any car you've driven. I've noticed this on a number of stock cars which then had lower profile and wider width tyres installed, and these include, swifts, hyundai excells, commodores, magnas, old ford panelvans.. not exactly a full range of "performance vehicles" but an ok inidication to learn by experience that diff tyres make a huge diff to the drive handling.

ride feel with lower profile tyres will introduce more to alot more bump in comfort.. and it will also introduce more road noise as more surface area of the wheel is in contact with the road AND as the tyrewall is thinner and doesnt loose as much vibration, so this all translates into the cabin.

however:

handling around corners is SIGNIFICANTLY improved. You can corner at much higher speeds without loss of traction

stopping from 100-o kph is significantly faster due to less ability to skid and better traction to the ground as there is SIGNIFICANTLY more surface area of all four wheels making contact to the ground.

Aqua plaining in the wet can be reduced by a large amount by choosing a tyre which has decent wet road handling. them dunlop and pirrelli drago series ones with the big groove in the middle handle very very well. My current p6000's handle very well in the wet and even on a bumpy road i had serious difficulty trying to get them to skid. mind you my car is probably alot lighter than an ignus.. but thats not the point. granted a heavier (not heavier by 2 tonnes, but by 500kg) car will have different handling dynamics, but only to a point. AND I'm comparing this to the stock wheels which were on my car when i originally bought it. in the wet, the stock ones were adequate for a standard driver, but not for an enthusiast, and safety actually is a concern to me.

secondly, yes, your reasoning for pressure distribution appears sound on the surface, but in the reality of physics, the more contact area you have to a surface, means better rolling friction equating to better traction. irregardless of the condition of the surface (wet./dry etc). While yes, starting friction may be increased, it's result, at the end of the day, is so negligable- its basically a number which has no real value in the real world. I dont think anyone is going to notice how they had to press the accelerator down 1/2000 of an inch more with 17" wheels vs stock versus when reversing out of the driveway.



while, yes, 17" alloys would probably be heavier than 15" standard rims, (not alloys), the weight difference gained isnt going to impede more than 0.1 seconds to a quarter mile time. THe simple fact of the matter is that you can weigh your own tyres, then go to a tyre shop and ask how heavy the 17" rims are (of your choice). that would eliminate all doubt, and its not exactly rocket science to do.


If your rolling diameter is increased then yup, it will slow down your acceleration and will knock out your speedo, so yeah, keep the diameter the same. The price of fashion for a car is not worth constant speeding fines. but thats Me opinion only...


And PatriotUK, keeping the gearing standard, will keep your speedo/your accel times etc standard.

sorry to but in, but this thread was starting to irritate me.

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 Post subject:
PostPosted: Tue Dec 14, 2004 1:38 pm 
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If the circumference of the wheels increases, it must alter the acceleration and top speed, because for every one time that the wheel turns, you travel further than with smaller wheels.
example. Lets say that at 70mph with the standard wheels, the wheel turns 30 times per second.
If the wheels are bigger, and turning 30 times per second, the increased circumference means you will be going faster.


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