Do people get bigger wheels just for the aesthetics? Is there a performance benefit?

[Mental]

Originally Posted by cs123

I think the Mazda guys was making the point that it's not the weight, it's the radius of gyration that can affect acceleration and braking performance.

As you increase the rim size you more than likely will increase the radius of gyration and this will have an affect, although I'm not sure what the real world impact is.

You also need to start looking at maintaining the strength while keeping the mass of the rim under control.

Someones on the ball. I don't have the maths for it, but even if the rim is only a couple of kilo's heavier, the mass of the rim is now 2 or so more inches further out. Meaning that it has a greater surface speed compared to your old 14" rim. Thats where the extra energy is needed to accelerate or brake a bigger rim.

[Rev28K]

Bring on carbon composite wheel rims with aluminium hubs!!

The American car engineer/designer Pete Brock pricked up his ears when he heard about the solar racers outcornering their support vehicles. The racers which were designed for straight line efficiency on spindly narrow lightweight wheels on low-resistance tyres where outcornering the utes and pickups. He reckoned that lighter wheels had a cascade effect on a car design – lighter control arms, lighter unsprung mass, lighter mounting points, smaller brakes required, etc. Start off with light wheels and the resulting car is a lot more efficient.

It absolutely killed me when my dedicated track wheels (Honda Enkei CRV alloys) were slightly heavier than my road wheels (Honda Enkei Type R alloys) but at only $100 each they were hard to knock back.

Metal weighs more than rubber and Porsche (engineers not the marketing people) were saying anything under 50 series tyres are hard to justify.

Have a look at how heavy the DUB style chromies are for a scare when compared to stock alloys or even better forged alloys.

[4Vman]

The lower you go in tyre profile the more "onus" you place on the cars suspension to do its job properly. Low profile tyres rely on the cars suspension to absorb all the bumps and control deflection as well as maintain proper tyre contact with the road..
Unless you drive on billiard table smooth roads all the time tyres with too low a profile can actually reduce handling performance.

[blueoval]

This is a good thread guys. I didnt have much of an idea on 'unsprung weight' and the like. But it seems as though, if you want your car to look good, handle well, and be affordable. Wheel diameter should be no bigger than 18"?

Personally speaking I am in 2 minds. I like the 15" Centreline's/Welds on old skool cars, but I also like seeing 17-18" simmons on them too or similar. Both styles are excellent wheels. Could convo's be use on track work? I dont know.

[4Vman]

Originally Posted by blueoval

This is a good thread guys. I didnt have much of an idea on 'unsprung weight' and the like. But it seems as though, if you want your car to look good, handle well, and be affordable. Wheel diameter should be no bigger than 18"?

Personally speaking I am in 2 minds. I like the 15" Centreline's/Welds on old skool cars, but I also like seeing 17-18" simmons on them too or similar. Both styles are excellent wheels. Could convo's be use on track work? I dont know.

Centrelines and convo's are extremely light wheels but they are relatively soft and damage easily, i personally wouldnt want to place much lateral load on those kinds of rims, they're designed for straight lines, i.e drag racing.
I know someone with weld pro stars and he did a hill climb in his XB and the cornering loads bent the spokes of the wheel and caused it to seperate and deflate..

Here's a pic: quite scary when you see what a bit of spirited track driving does to these types of rims..

http://img.photobucket.com/albums/v5...ltofA0032R.jpg

[atec77]

Originally Posted by myts

Nothing like the sight of 305/55 15's under the back of a Falcon coupe. Next to that your 235/35 20's do look like they belong on a pulsar.

and the 15" will provide better traction and braking .

[xbgs351]

Originally Posted by Rev28K

Bring on carbon composite wheel rims with aluminium hubs!!

The American car engineer/designer Pete Brock pricked up his ears when he heard about the solar racers outcornering their support vehicles. The racers which were designed for straight line efficiency on spindly narrow lightweight wheels on low-resistance tyres where outcornering the utes and pickups. He reckoned that lighter wheels had a cascade effect on a car design – lighter control arms, lighter unsprung mass, lighter mounting points, smaller brakes required, etc. Start off with light wheels and the resulting car is a lot more efficient.

I passed three cars descending Mt Buffalo on my pushbike on Christmas day. I generally pass more cars than that descending Mt Hotham.

Originally Posted by Rev28K

It absolutely killed me when my dedicated track wheels (Honda Enkei CRV alloys) were slightly heavier than my road wheels (Honda Enkei Type R alloys) but at only $100 each they were hard to knock back.

Metal weighs more than rubber and Porsche (engineers not the marketing people) were saying anything under 50 series tyres are hard to justify.

Have a look at how heavy the DUB style chromies are for a scare when compared to stock alloys or even better forged alloys.

My race car has 13 x 9.5" and 13 x 11.5" rims with some nice sized tyres. If I ask someone to lift them, they just about heave them over their heads as they are so much lighter than ordinary wheels and tyres.

[blueoval]

wow, that is amazing 4Vman. I can see the logic. Depending on application, its better to get wheels to suit what you do.

Do you think the width of the rim had any effect on why that wheel buckled like that?

[Disciple]

If you want the best compromise, get some 18" rims and buy some quality rubber for them - Michellin, Pirelli etc. If you wanna be hardcore, import some Advans, or Volk/Rays or something. They're extremely light weight racing rims.

[4Vman]

Originally Posted by blueoval

wow, that is amazing 4Vman. I can see the logic. Depending on application, its better to get wheels to suit what you do.

Do you think the width of the rim had any effect on why that wheel buckled like that?

The wider the rim the more tyre you have and "generally" the more cornering load you can sustain.. wider rims will just make this problem worse..
xgs351 is spot on about rims dia.. the brake dia generally dictates the rim dia used, i.e for racecars, especially open wheelers they use the smallest dia possible dictated by brake caliper clearance, that way they maintain as much sidewall as possible to aid tyre life and durability as well as some cushioning by the tyre to maintain contact with the track..
Of coarse with heavier cars like sedans too much sidewall will make steering vague and create too much sidewall flex so there has to be a balance as well.

[Bossxr8]

Originally Posted by xbgs351

Race cars generally run 13" or 15" wheels, and by race cars I mean open wheelers. Formula 1, Formula 3, A1GP run 13" and Indycars/Champcars run 15".

Sports and prototype cars (ie Lemans) are heavier and hence need bigger diameter brakes to haul up the cars. To fit over the brakes, these cars need bigger diameter wheels. This is also why Indycars/Champcars run 15" rims compared to 13" rims on F1 cars, as the Indycars/Champcars are around 135kg heavier and don't have carbon discs.

F1 cars have such small rims and huge tyres because the tyres are used as a form of shock absorber, the suspension does very little in terms of absorbing bumps, the tyres are designed to do that.

I remember reading a little while ago that once you go lower than a 40 aspect ratio for tyres you start to lose sidewall strength and handling decreases. So for Falcons thats usually a 17 inch rim, the same as used by V8 Supercars.

[blueoval]

hmm makes a lot of sense. I for one would want handling performance over looks. But if you can get both, then your winning. Of course depending on your application.

For me, its handling and straight line performance for street only, so in saying that, it would have to be a wheel between 15-17" with a width of no less than 7". On a falcon that is.

[xbgs351]

Originally Posted by Bossxr8

F1 cars have such small rims and huge tyres because the tyres are used as a form of shock absorber, the suspension does very little in terms of absorbing bumps, the tyres are designed to do that.

I remember reading a little while ago that once you go lower than a 40 aspect ratio for tyres you start to lose sidewall strength and handling decreases. So for Falcons thats usually a 17 inch rim, the same as used by V8 Supercars.

With a monoshock for instance, both wheels can move up or down together and the car can roll, but one wheel can't move up by itself, so yes the tyres are an important part of the suspension. Monoshocks separate roll and bump forces better than the conventional system with two bell cranks and separate coilovers. Triple shock systems are also used.

[Ives]

Originally Posted by Steffo

What exactly were the Pro's? Beside how it looks...

I feel with bigger wheels, the car has got more grip cos I feel the car's much more planted on corners. However, it might be the different tyres I have on.

[Bucknaked]

I've got 19's. Can only go as fast as the speed limit. Doesn't matter how quick your car is or how big the wheels you'll still hit the speed limit.

[Nikked]

Originally Posted by xbgs351

Race cars generally run 13" or 15" wheels, and by race cars I mean open wheelers. Formula 1, Formula 3, A1GP run 13" and Indycars/Champcars run 15".

Sports and prototype cars (ie Lemans) are heavier and hence need bigger diameter brakes to haul up the cars. To fit over the brakes, these cars need bigger diameter wheels. This is also why Indycars/Champcars run 15" rims compared to 13" rims on F1 cars, as the Indycars/Champcars are around 135kg heavier and don't have carbon discs.

don't for get on most open wheelers the side wall accounts for 1/3-1/2 or suspention travel...

[Ruger]

I went from 195/65/14 to 205/40ithink/17 on my e30. handling improved 1000 fold. im not sure whether its the tyre but before the car slid all over the place and handled no better than a ba xt falcon.
The overall diameter of the wheel and tyre is just a touch smaller than the 14's because of the tyre profile but the difference in handling was phenomenal.
The new tyres are chinese brand jintong and the old ones were falken. go figure.

[BHDOGS]

when it comes down to it most people who fit 18inch and up wheels are doing it for looks if you were serious about track days and hill climbs youd obviously set yourself up that way but for most regular joes i doubt there would be much diffrence when your doing 60.

[Nikked]

even if you bought a wheel for racing and for its advantages in weight/strength/perfomance, your still going to choose one that looks good in the end...

[xbgs351]

Originally Posted by Nikk O'lass

don't for get on most open wheelers the side wall accounts for 1/3-1/2 or suspention travel...

In the ground effect days, the springs were that stiff that the suspension movement came from the suspension arms bending.

It is also worth mentioning that open wheelers don't run a lot of tyre pressure. My car cold runs 14 PSI front and 16 PSI rear.

[Steffo]

Originally Posted by Ives

I feel with bigger wheels, the car has got more grip cos I feel the car's much more planted on corners. However, it might be the different tyres I have on.

That would be a combination of possibly better tyres, and the fact that the 74kW 146Nm engine through an automatic gearbox was struggling enough with the standard size wheels already, it can barely turn those 17s.

[Rev28K]

Originally Posted by xbgs351

My race car has 13 x 9.5" and 13 x 11.5" rims with some nice sized tyres. If I ask someone to lift them, they just about heave them over their heads as they are so much lighter than ordinary wheels and tyres.

I went to the Melb Grand Prix last year and was talking to the RMIT university racing guys. (Love the uni racing idea - KISS and engineering > bs.)

I’d just read about the Dymag (UK) composite wheels and mentioned it to them, they pointed me to their own composite wheels and suggest that I try lifting them. Incredibly light.

Tried lifting one of the Porsche 911 BBS racing wheels (rear) later on and they were much heavier than I was anticipating.

[Fev]

the biggest i will go is 18" and ill have them either 8" or 9" wide. i cant afford wider :P
ive got 17x8's atm and they are alot better then the 16x6 stockies