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Model specific boards => Golf mk5 => Topic started by: LaserBlue on 20 April 2008, 09:22

Title: bigger wheels make it slower?
Post by: LaserBlue on 20 April 2008, 09:22
is this true??

reason i ask is last night i drove my mates gti all standard like mine but with 17s

soon as i started driving i could tell straight away how much the comfort changed compared to mine with 18s on then after a while i i went home and mine felt slower?

its hard to explain what im saying but with the 17s it seemed faster and defo more comfortable.

mine did come with 17s since i had the 18s i noticed more rattles..

anyway id already put my s3 alloys up for sale few days ago

thinking of putting the 17s back on as i commute to work on the motorway and i want that smoother ride back.
Title: Re: bigger wheels make it slower?
Post by: pulp58 on 20 April 2008, 09:36
Not sure about this.

I remember reading that the Astra VXR's official 0-60 time could only be acheived with the optional 19" wheels, so there was an obvious benefit with that car of having large wheels.

I would have thought performance wise regarding pace, it was the same, handling - bigger wheels should have benefit. Ride - 17"s would be best as you found with your mates!  :cool:
 
Title: Re: bigger wheels make it slower?
Post by: NewGolf on 20 April 2008, 09:39
I chose 17"'s over the 18"'s after reading about it on a GTI review. It's definatley a smoother ride, although the car doesn't look as mean!
Title: Re: bigger wheels make it slower?
Post by: R32UK on 20 April 2008, 09:58
I remember reading an article in some magazine where they tested to see of bigger wheels made your car any faster. Round a track the smaller wheels came out on top. It was quite an extensive test but was a while ago so my memory is a little vague. Definately something behind that theory is what they proved.

Stupid stupid memory :undecided:
Title: Re: bigger wheels make it slower?
Post by: LaserBlue on 20 April 2008, 10:03
because the wheel has a bigger circumference it takes that little longer to turn therefore being slower than a smaller wheel which will turn quicker and stop faster?

kinda what im thinking??

 :huh: :undecided:
Title: Re: bigger wheels make it slower?
Post by: CocoPops on 20 April 2008, 10:04
What tyres are fitted to the 17s and 18s as standard?
ie are the rolling radii the same?
Title: Re: bigger wheels make it slower?
Post by: bobotheclown on 20 April 2008, 10:05
Theoretically, if you have a hub spinning at 100rpm, a tire with a 20-inch outside diameter would propel the car twice as fast as a tire with a 10-inch diameter. In actual practice, installing larger tires on a car, will make it accelerate much slower, but increase your top speed, if your vehicle has the horsepower to push it. A new wheel that is 8% larger than the old wheel, will push you 4mph faster at the same wheel speed. - From Yahoo Answers (quick google search)

Upshot, faster top end speed, slower acceleration.
Title: Re: bigger wheels make it slower?
Post by: NewGolf on 20 April 2008, 10:05
I think the 2 wheels, 17 inch and 18 inch have different profile tyres, so the rolling radius(!) should be identical. If it wasn't the speedo would be out?

225/45/17 as opposed to 225/40/18  I think from memory ?
Title: Re: bigger wheels make it slower?
Post by: Cass on 20 April 2008, 10:14
I think the 2 wheels, 17 inch and 18 inch have different profile tyres, so the rolling radius(!) should be identical. If it wasn't the speedo would be out?

225/45/17 as opposed to 225/40/18  I think from memory ?

Correct.

Cass
Title: Re: bigger wheels make it slower?
Post by: LaserBlue on 20 April 2008, 10:16
yes thats correct about speedo out..

i had 225 40 18- 8j on my old bmw and my speedo said 30 but i was doing 32!!

so smaller tire = faster acceleration - bigger tire = better top end speed

18s look nice but i think i will be going back to the 17s..
Title: Re: bigger wheels make it slower?
Post by: NewGolf on 20 April 2008, 10:19
 :grin: Glad i chose 17's!  :grin:
Title: Re: bigger wheels make it slower?
Post by: gangeox on 20 April 2008, 10:22
This is my 2 penneth worth from what i can remember from college all them years ago:

Bigger wheels give better acceleration.

I you look at it like a 5 speed racing bike if you use a large cog on the front and the big cog on the back you pedal like mad and get nowhere, (i.e. this is used to go up hill) if you use the large cog on the front and the small cog on the back you go faster but at slow speeds its harder to pedal.

However if you use bigger wheels but with a low profile tyre to give the same circumference as the small wheeled tyre it will stay the same.
Title: Re: bigger wheels make it slower?
Post by: Spaced on 20 April 2008, 10:30
Nice to see some love for the standard 17s, I think they have a chunky more purposeful look, and at night in the right light it is difficult to see the difference between the 18s.

Does anyone know the official weight of the 17 and 18 inch Monza?

Title: Re: bigger wheels make it slower?
Post by: NewGolf on 20 April 2008, 10:53
I'd guess the 17's would be lighter as theres an inch less metal! Unsprung weight mass uses the 1:4 ratio from memory, so if they weigh a pound less each wheel x 4 = 16lbs less unsprung weight from the car. It "should" accelerate faster. Low rolling radius should equal fast acceleration, whereas high rolling radius equals lower acceleration but higher top speed.

"Puts his old school physics books back in the loft!"
Title: Re: bigger wheels make it slower?
Post by: 182_blue on 20 April 2008, 11:16
there would be minimal speed loss if any, you really would notice it imo, perhaps his was just quicker out of the box or run in differently etc, as for comfort then the smaller the better (or the more rubber the better), then again it wont be as good in the bends and imo doesnt look as good, swings and roundabouts i guess, i read an article somewhere where someone was saying that bigger alloys put on by car makers were killing the ride of most modern cars, and i guess its true
Title: Re: bigger wheels make it slower?
Post by: JonnyG on 20 April 2008, 11:18
In EVO's tyre test last year they found their test GTi was faster on 17"'s rather than 18"s.  They commented on the better turn in and bite with the 17" Bridgestone Potenzas, and they were 2.5 secs quicker than the 18"s Potenzas around a wet track

Personally I found the difference in ride to be very subtle, and not a big difference

But looks wise I much preferred the 18"'s  :drool:

(http://i69.photobucket.com/albums/i64/Jerry_G/WholeCar.jpg)
Title: Re: bigger wheels make it slower?
Post by: 182_blue on 20 April 2008, 11:22


only problem with that pic is as the 17s are closer to the camera they look bigger than the 18's LOL

but yes deffo better looking  :cool:

oh and i remember that article, it was more about grip though than outright speed (ie grip allowing more speed around the corners), i guessed (possibly wrongly) he thought it felt faster pulling away etc
Title: Re: bigger wheels make it slower?
Post by: JonnyG on 20 April 2008, 11:30
only problem with that pic is as the 17s are closer to the camera they look bigger than the 18's LOL

Yes, could'nt risk it falling backwards onto the car  :shocked: :rolleyes: :laugh:
Title: Re: bigger wheels make it slower?
Post by: Hurdy on 20 April 2008, 16:21
The difference in inertial weight will be negligible, I would have thought :undecided: and so a reduction in accelleration would only be very small.
Similarly you could argue for and against 17" on handling too

a. A smaller alloy gives more in the wall of the tyre and therefore there is less grip....or
b. The smaller alloy gives more in the wall of the tyre and therefore holds on longer in the corners

You decide :undecided:
Title: Re: bigger wheels make it slower?
Post by: LaserBlue on 20 April 2008, 17:09
yeah the 18s do look far better but i dont know why they gave them that shiny look.. not my cupatea

anybody powercoated any or sprayed them another color?