How does a larger rim effect the car

[SteveJH]

Originally Posted by F6E

Point taken, But we are still taking the tyre out of the equation, Rim and tyre rotate as one, their combined mass acts as one, they do not differentiate where the bead meets the rim, their respective masses are not that dissimilar ....
Surely a 25kg 20" rim/ tyre combo has the same inertia as a 25kg 18" combo ?

That isnt the argument though.

The arguement is that a 20" rim/tyre combo will weight more than an 18" rim/tyre combo if the same rim design is used.

[zilo]

I put 8 piston calipers on one of my cars and was forced to get bigger rims.

It is a hidden cost in a brake upgrade that most people don't consider till they try to put the wheels on their new Brembo package ..

So those people upgrading their brakes usually have no choice....so doesn't matter what effect it has...you gotta do it sometimes and is prolly why HSV and FPV do it.

[Shonky.]

Originally Posted by shonkymofo

I reckon 20s are a mistake if you care about anything other than looks

Originally Posted by F6E

Should we let HSV in on this ?

HSV consistently smashes FPV in the ride/handling stakes in every comparo ( even in the latest FPV/HSV/SRT face off, the Clubbie had a win based on being a better steer, even when slower in a straight line ).

Ugly, Clown Face cars, I know, but they handle ( and on 20's )...go figure...

Far from a controlled experiment though.......

That is, do you think there are any other material differences between the cars you list other than 19 inch tyres vs 20s?????

oh, and of course you are comparing handling based on a magazine article too...........

[mik]

Originally Posted by F6E

Point taken, But we are still taking the tyre out of the equation, Rim and tyre rotate as one, their combined mass acts as one, they do not differentiate where the bead meets the rim, their respective masses are not that dissimilar ....
Surely a 25kg 20" rim/ tyre combo has the same inertia as a 25kg 18" combo ?

i reckon most blokes doing the 20`s would go wider, more rim , more tyre = more weight, yes you can get lighter rims, but for pot holed roads would you want them? more weight at the extremities of the wheel = more stress on steering, gyro effect? wider rubber = more stress on steering due to more friction? extra weight = needs more damping to keep wheels on the ground
see what happens when you move weight closer to the centre of a spinning mass, i`m thinking it would also work in the reverse upon acceleration, it would take more energy to overcome the mass if it`s further out, WHY IS IT SO??? you old guys will like the second clip .
http://www.youtube.com/watch?v=AQLtcEAG9v0
http://www.youtube.com/watch?v=0M9OM...ture=endscreen

[FGII-XR6]

had a mate with 20s on a BA kept stuffing them on potholes ( more pothole than road around here) he now has factory 17s and problem solved

[aussie muscle]

while i find narrow profile tires looks better, i prefer the comfort from bigger sidewall tires over our nasty, pot-hole-ridden roads.

i've heard some say that a tall sidewall flexes more under race conditions, so lower profile tire is better for racing.

Originally Posted by Sprint

Perfectly true with Physics, Momentum and Inertia, Imagine a small spiniing top on the end of a stick, change of direction might not seem hard.

try spinning a bicycle wheel in your hands and change it's direction. it takes quite a lot of effort.

[Nikked]

Race cars still need side wall flex to help heat the tire.

[AWD Chaser]

I have 20" rims on my HSV. I used to have a VX Senator with 18" rims and I prefer that then my current LP 20s.

Because of stuff all tyre wall, I have had rim damage due to pot holes, put up with a bumpier ride, and am not able to put 100% power to the ground (more tyre wall absorbed torque, and reduced wheel spin).

The only benefits I have found for LP is some cornering (less roll), and IMHO, it looks better... For me however, this doesn't outweigh the negatives, and I am considering downgrading to 19" rims...

[Bossxr8]

The HSV TopGear tested had 22 inch wheels, which is why it went backwards.

[svo supporter]

Originally Posted by aussie muscle

while i find narrow profile tires looks better, i prefer the comfort from bigger sidewall tires over our nasty, pot-hole-ridden roads.

i've heard some say that a tall sidewall flexes more under race conditions, so lower profile tire is better for racing.


.

Very few classes of race cars run low profile race tyres....The majority are high profile stuff....So your post isn't quite true.

[2011G6E]

I personally know three people out here who have shattered or cracked factory 19" rims on XR6T's (yes, all three were XR6T oddly enough).

I was, for once, watching some V8 supercar racing, which I hadn't done for a long time, and thought the rims looked a bit "small" with a high profile tyre. I did a bit of searching on the internet and was honestly shocked to see that they use a standard 17" rim! Then again, Formula One cars used a 13" rim (not entirely sure if they do now though, but they're not big), so the excuse that you absolutely need them for "handling" is a bit of a Furphy...

...not exactly sure why we need 18, 19, or larger rims on street cars on typically crap roads in the real world...I firmly believe they're a marketing ploy that has been foisted on the public who now think they are necessary on anything "sporty"...

[F6E]

Originally Posted by 2011G6E

...not exactly sure why we need 18, 19, or larger rims on street cars on typically crap roads in the real world...I firmly believe they're a marketing ploy that has been foisted on the public who now think they are necessary on anything "sporty"...

On that note;
I'm not exactly sure why we need turbos on our cars ? After all the roads are crap (apparantly), the max speed limit is 110, you do a burnout and the do- gooders can crush your ride....a n/a 4.0 I6 Is more than adequate for day to day driving and towing duties....

So
why turbos / superchargers ?
Why lowered suspension ?
Why mod for more power ?
Why bigger brakes ?
Why bigger wheels?


Why ? Coz we can !!

Don't like it ? Camry time maybe?

[Nikked]

Originally Posted by 2011G6E

Formula One cars used a 13" rim (not entirely sure if they do now though, but they're not big), so the excuse that you absolutely need them for "handling" is a bit of a Furphy...

F1 cars have the smaller rim for a few reasons, one to limit Limit brake size, and the taller sidewall allows the suspention to be stiffer etc...

[Raptor]

It comes down to what you value more?

Fashion or Function

Or as we used to say;

Show or Go

Everything comes with a compromise.

[Jack960]

found a set of 19's that weigh 14kg each made of a high strength alloy load rated at 890kg each. so I have met half way, still look good with a bit more wall then 20's.

[Blem]

I have the stock FGF6 twisty 245/35/19's. They each weigh 25.5-26kgs with tyres.
I have stock BAXR8 track rims 235/40/18's. They weigh just 24.5-25kgs with tyres.
After my last track day I left my track set up on for a few weeks.
The track rims have semislicks. They have MUCH stiffer sidewalls & made the car twitchy on the road.
So sidewall composition is an important factor.

[Sioso]

I have 2 sets of rims for my monaro:
19x9 all round another set 18x9 all round
On the bumpy country roads where i live the slightly increased sidewall of the 18's make it much more compliant and easier to drive quickly.
The 19's tend to skip and break traction.

19's look better and are fine on smooth roads but overall the 18's are better to drive on.