It may sound stupid but I'm sure I read in a car mag that fitting bigger wheels will make you go slightly slower! Does anyone know if this is true????
After having my 17's fitted the car does feel like it takes slightly longer to pick up speed.....maybe its just in my head though:wacko:
If anyone else has heard of this let me know please

It is true that it makes your car a little bit slower because of the bigger wheel-diameter.
i´m sure you notice a big difference when you put your winter-tyres on, they usually is standard 14" on your car.

depends on what you mean by bigger, if you put wider tyres on you increase rubber/road contact therfore you get more rolling resistance. That will slow you down a bit.

Yes you will mate the car will be slower to accelerate but should have a slightly higher top speed.

Simon

Whatever you do, I suggest you make sure the overall diameter of the wheel remains the same. I believe you understand that 17 inch wheels necessitate the use of lower profile tyres in terms of maintaining it. Do the math.
You are refering to a kind of 'urban legend', that those huge tyres on those shiny 18's will kind of 'muffle' the car's performance. There is a rationale here I believe because the two parameters here are aerodynamics (wider frontal surface of the tyre) and weight of course, due to the greater mass of the wheels.
Then again, it is logical to assume that accelaration with 1st and 2nd gear should be better, thanks to better grip.
To cut a long story short, I've read a test on that, a long time ago. I can't quote it, don't even remember the magazine, but I remember that the differences were so slight that we shouldn't be bothering. Differences that normally can't be noticed by the driver. On the other hand handling improves big time.

Just as long as you don't overdo it. Like a cousin of mine. Who had 345 tyres on his Suzuki Samurai. LOL.

Depends on the weight of the alloy ..

You can get bigger/lighter alloys and that'll make the wheels have less inertia .. therefore spin more freely.

There are quite a few lists on the net regarding wheel weights (I have a few links at work I can dig out)

But it's the rolling radius that will really change your actual acceleration (I've also got links to an online calculator for this at work) .. change your rims (with the same profile tyre) to 12" and you'll fly off the line but have no top end. Change to 24"s and it'll take you an age to get there but your top end would be higher.

Also remember that tyres weigh quite a bit too .. re-moulds and run flats being the worst offenders.

Then you have to deal with unsprung weight, tyre widths etc .. it can get quite technical. I still think the best thing is to buy good tyres to grip the road and stop wheel spin.

B.

replacing the standard stock yaris wheels with the 17's u have, assuming ur using a 205/40r17 tyre...

your speedo reading will be 2.2% slow at all times, in other words; yes your 0-60 etc etc is 2.2% slower

e.g. when your speedo reads 60mph you will actually be doing 61.3

however your car will clock up miles 2.2% slower as well

QUOTE

your speedo reading will be 2.2% slow at all times, in other words; yes your 0-60 etc etc is 2.2% slower

i thought is the other way round if you put wider wheels and tyres then your speedo will show more then it is

Okay, my understanding:

Bigger wheels will mean slower accleration, but higher top speed..

Your speedo wont be out as long as you follow the rolling radius rules..

how do ya work that 2.2% thing out

i was sure my yts would be slowed up by the 17's but it didnt seem too bad

its probably a touch slower because of there being more metal - therefore more weight, but other than that its fine. i worked it out that the rolling radius from the original 15's to the new ones was almost the same.

the difference in acceleration will be negligible, hence it might seem only very very slightly slower

bigger wheels usually means more weight, and it also takes longer for the wheel to complete a turn

even if the radius is only slightly bigger it will still be slightly slower than stock


when i changed the wheels on my yaris the 15's i put on were slightly smaller than the stock radius so I get slightly more acceleration and less top end, which doesnt really matter to me anyway because i'm not interested in top end

it's very difficult to notice the difference until ur either matched at the lights with the same car as yours, or you step out of ur car and into a stock one straight away

Rolling radius baby, rolling radius.

If you ignore weight, and drag, as long as the overall radius is the same, then no it wont make a difference. But with smaller wheels and low profile tyres your acceleration will be quicker, but will reduce top end speed. But with bigger wheels, and say, same profile tyres, the your acceleration would be reduced but the top end increased.

Thanks for the replies they were very ehhh technical......it has definetly answered my query..... I'm more than happy with my 17's and I would recommend to anyone thinking of fitting 17's to just do it!!!

Im sure you can tell the difference in launching and cornering if you put 18's on it. It would lag noticable but with more grip. My mate put 18's on his lancer (wich is silly) and all he got out of it was harsh ride and hole in the wallet for tyres and insurance.

Im leaving my sportivo stock. Simple.

I took a S170 Focus 2.0L manual for a test drive yesterday, it sucked. That car has really poor ride quality, great for track but not for normal everday roads. I blame the 17inch alloys and wide footprint. The sportivo shits all over the focus in ride quality for street drivin. And I bet around the track. I will open up a new topic about my impression of the new 'hot focus' in OZ..

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Hello 2ZZ-GE Sportivo,

in addition to what u said about the Focus ST170 look at this maybe u'll find it interesting
http://www.passion-focus.com/ST/moniteur.htm.

QUOTE (Yarisboy @ Aug 18 2003, 10:14 PM)

replacing the standard stock yaris wheels with the 17's u have, assuming ur using a 205/40r17 tyre... your speedo reading will be 2.2% slow at all times, in other words; yes your 0-60 etc etc is 2.2% slower  e.g. when your speedo reads 60mph you will actually be doing 61.3 however your car will clock up miles 2.2% slower as well

just adding ..

fitting wheels whith larger rolling radius will as Yarisboy decrease the speedometer reading, as the wheel will take a longer distance to roll once .. but as the speedomenter from the factory will read too much anyways, your speedometer will actually be more correct

try taking the car on a dyno where you'll be told what the mis-reading is on the speedometer - mine was 5,2% - driving 95 km/h when showing 100 km/h

which I found odd, having tried driving with a GPS showing that the car misread 3,5% .. well, don't think to much about that

at Toyotaextreme under the menu "bilen" .. choose "dæk/fælg beregner" and there you can put in what standard size wheels your car has and what size you wish to compare it with - then you'll be told by what % your rolling radius will be changed.

QUOTE (2ZZ-GE Sportivo @ Aug 19 2003, 11:58 PM)

Im leaving my sportivo stock. Simple.

I thought about the lowering kit too, but in the end decided that I liked
the ride as is. I have to do 50 miles commuting every day on rubbish
roads, and didn't think stiffening the car for a bit of extra cornering
speed justified the reduction in comfort.

That's not to say that the factory spec. car isn't a lot of fun on the
roundabouts

Cheers

Paul.