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

[GTS_300_Coupe]

According to Mazda6tech (the man certainly *seems* to know what he's talking about) up-sizing your wheels is just for looks and you stand to lose in terms of handling and performance (especially acceleration and braking.)

Read here:
http://www.mazda6tech.com/index.php?...d=44&Itemid=50

Plus-sizing for Dummies

Larger diameter wheels:

Larger diameter wheels bring a more prominent aesthetic touch to the car. Many Mazda6 owners choose to change out their 16" wheels for 18's, or their 17" wheels out for 19's. These large wheels are attention-getting, and can make a statement about you and your car.
Care to know what that statement is?

Aside from looks, there is really only one great reason to change to a larger wheel size: to fit larger brakes. Do you need larger brakes? If, after a day of hard driving, you can still lock your brakes- then no. And even then, you should consider swapping your brake pads before your rotors.

There are, however, many compelling reasons not to plus-size your wheels that you should be aware of before purchasing new wheels:

1. Reduced braking distances. Larger wheels, even if they weigh the same as smaller wheels, are harder to slow down. [Further reading.]

2. Reduced brake pad life. Because of #1, the brakes must work harder. Expect them to wear more quickly, or in hard driving possibly overheat and fail.

3. Reduced steering feel. Due to gyroscopic effects, larger wheels are harder to turn left and right. Thus, a slipping wheel will not transmit as immediate nor as strong of a force to be felt through the steering wheel. Running a different wheel offset changes the car's scrub radius, which can multiply this effect.

4. Reduced acceleration. Larger wheels, even if they weigh the same as smaller wheels, are harder to speed up. [Further reading.]

5. Reduced gas mileage. Because of #4, your engine needs to work harder to accelerate the car. Highway mileage, where the car remains a constant speed, will be unaffected. However mileage in stop-and-go traffic will decrease.

6. Reduced integrity of the wheel mounts. Because of #1, #3, and #4, large wheels can actually put a dangerous load on the wheel mounts- the axle, hub, ball joints, bearings, and other load bearing parts.

7. Reduced integrity of the wheel. A larger wheel can be (be is not necessarily) more fragile. This is due to a manufacturer not increasing the spoke and rim strength proportional to the increased forces exerted on the wheel. This might be done to save cost or weight. To compensate, large wheels can be forged or pressure-cast, but this makes them expensive. Even forged 19" wheels are still heavier than most inexpensive, cast 17" wheels, and not necessarily as strong.

8. Increased ride harshness. Without much sidewall on the tire, the tire can no longer absorb bumps. It will try, however- low profile tires have very soft sidewalls to compensate. A soft sidewall will tend to deform, which is one of the reasons low-profile tires tend to require wider wheels.

9. Increased chance of tire bubbles, blowouts, and/or wheel damage. Since the low-profile tire cannot absorb as much impact, the entire combination becomes more delicate. This risk is increased by running a narrow tire.

10. Decreased ride quality. Larger wheels often (but not always) increase unsprung weight. Ride quality is largely determined by the car's sprung to unsprung weight ratio, where a larger ratio is better. A car with heavy wheels will need to run softer springs (hence increasing body roll and dive) to maintain the same ride quality.

11. Price. Large wheels are expensive. Since most 19" wheels need to be forged for reasons of reliability, they can cost two to four times as much as a 16-17 inch wheel.

12. Price. Large tires are expensive to continually replace. This can amount to roughly a $150-$300 savings ever few years- that adds up! All for the exact same width of tread.

Some plus-sized wheel combinations do give excellent grip, turn-in, braking, and overall handling improvements. This is not from the larger diameter of the wheel- it is despite the larger diameter. Those attributes are best improved by purchasing stickier rubber (more aggressive tires) on WIDER wheels.

Wider Wheels:
Moving to a wider wheel on the stock diameter (16" or 17" on the Mazda6) can provide great handling improvements.
It helps the tire's sidewall gain leverage in resisting cornering forces.

To achieve the same sidewall stiffness on a car with a skinnier wheel, the air pressure must be increased. Increasing air pressure has several undesirable effects, thus it is better to gain sidewall stiffness via a wider wheel.

The Mazda6 can accommodate an 8" wide wheel.
The benefits of a wide wheel are mostly limited to handling.
Acceleration and braking may degrade slightly if the wheel's weight has risen, though to a smaller extent than it would with a larger diameter wheel.

Much like large wheels look from the side, wide wheels look tremendously imposing from behind- so it's an aesthetic upgrade too.

The Real Upgrade: Tires!
Of course, the biggest upgrade for the Mazda6 is not the wheel- it's the tire. Upgrading to a tire with softer rubber will do wonders for improving cornering grip and braking distances.

A stiffer sidewall can drastically change the handling characteristics. In short, tires can make a world of difference and get you the performance you want- often without an expensive wheel upgrade. Tires are the single biggest upgrade you can buy for the car.

In fact, the most compelling reason to buy new wheels is to mount a second set of tires on them- have a set of winter and summer tires. Or all-season and competition tires. Either way- don't skimp on tires. Ever. [Further Reading.]

Next time you a car pulls up next to you with 19's catching your eye, enjoy how nice they look. In your rear-view mirror, that is, before they disappear in the next turn.

[El Sucio]

Probably why reasons you don't see V8 supercars (or most other forms of motorsport) running 18-19 inch wheels. They focus more on wheel width.

[Steffo]

Unless the car was designed for it, more diameter = slower car.

I know some retarded people who think a 20" wheel with a super low profile tyre will give better grip and performance then their car's original 16" wheel will. No extra width either.

[cob115]

dont know bout tall wheels but fattys are my favorite ,xa xb xc coupes were made for them

[Nikked]

Depends on what car, and what driving. If you are buying 20in chromies for your falcon (or what ever) its for the bling...

[Elks]

Originally Posted by cob115

dont know bout tall wheels but fattys are my favorite ,xa xb xc coupes were made for them

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.

[Dezza]

Personally, I go for fat tyres rather than large diameter. That's why I got the SVOs. They are 7" wide on the front, 8" on the back (compared to the old 6.5" turboblades) but are only 16" in diameter. They give it a tough stance.

[Ives]

I never regretted upping my wheel size by 2". All pros, no cons. Well, more expensive tyres, but meh...

[Nostalgia]

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.

Good comeback. Some do it for performance and handling but the majority these days do it just for looks.

[eXi7w0unD]

its really just for show like mine!!!!! and it helps me not to speed or do wheel spins etc i dun wanna spend 325+ for tread for 1 wheel..

[ea90gl]

i would have to agree on the whole enhancing look thing (provided you pick the right type), for instance when my fiance bought some 17's for her 06 lancer it looked so much better than the standard 14's with hubcaps, but the problem was it had a bumpier ride.

[fourl6]

Originally Posted by ea90gl

i would have to agree on the whole enhancing look thing (provided you pick the right type), for instance when my fiance bought some 17's for her 06 lancer it looked so much better than the standard 14's with hubcaps, but the problem was it had a bumpier ride.

found that when i went from my standard 16's to BF XR 17's... but it does handle alot better around corners but i think thats the width not the height... its not any slower but i only went up 1 inch...

[Barry_v]

I think he is over stating a lot of the real life effects of larger wheels. most of those things would not even be able to be measured their effect would be so small.

you could equally say say that a taller wheel gives you better fuel economy because it makes your final gearing taller.

[JC]

Originally Posted by Barry_v

I think he is over stating a lot of the real life effects of larger wheels. most of those things would not even be able to be measured their effect would be so small.

you could equally say say that a taller wheel gives you better fuel economy because it makes your final gearing taller.

That's true - his base assumption is that when you go for a larger rim size, you keep the same profile tyre, thus giving a larger overall circumference. That would be both stupid and illegal. When you go for a larger RIM size, you actually go for a lower profile tyre (and he does touch on the effects of that later, so who knows what he's thinking in points 1 to 4), which results in the same (or very similar) rolling diameter and circumference.

Yes, the weight of the wheel may be an issue in terms of momentum, but it's not like a 19" wheel is twice as heavy as a 17" - there'd be a couple of KGs per wheel in it, and you can get that just between different brands of the same size anyway.

Mazda6person hasn't really thought about what he is saying, or has only thought enough about each point, but not looking at the whole picture (or wheel).

[ebxr8240]

So whats wrong with these ??? LOL...
http://www.fordforums.com.au/attachm...chmentid=38158

[schnoods]

I think generally they started getting bigger from 14" then 15 and so forth due to the brakes behind em.

I reckon you'd have to be crazy to have anything bigger than 17" without sporting some Serious brakes.

Go the 15" Pro Convo's.

[Steffo]

Originally Posted by Ives

I never regretted upping my wheel size by 2". All pros, no cons. Well, more expensive tyres, but meh...

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

[Disciple]

Anything bigger than 19" in my book is stupid. I think 18's are the perfect size, hence why you see proper Japanese fast cars (Skylines, Supras, EVOs etc) all run 17" and 18" rims. It's all to do with unsprung mass in terms of performance. Reduce the unpsrung mass means better braking, better acceleration, cornering etc. IMO, 20's on a normal sedan or whatever look retarded and only serve to make the car owner look like a complete tool who knows nothing about car dynamics. Going to larger rims almost certainly means lower profile tyres which in turns gives rubbish ride quality. Most of the time you can't even buy decent brand tyres for bigger rims, so people go with brands like "Wanli" which are simply horrible.

[LTDHO]

I think 17 is about the best size, I ran these for years (v8 supers still do)

I have 20's now just for looks.

[merlin]

Originally Posted by Disciple

Anything bigger than 19" in my book is stupid. I think 18's are the perfect size, hence why you see proper Japanese fast cars (Skylines, Supras, EVOs etc) all run 17" and 18" rims. It's all to do with unsprung mass in terms of performance. Reduce the unpsrung mass means better braking, better acceleration, cornering etc. IMO, 20's on a normal sedan or whatever look retarded and only serve to make the car owner look like a complete tool who knows nothing about car dynamics. Going to larger rims almost certainly means lower profile tyres which in turns gives rubbish ride quality. Most of the time you can't even buy decent brand tyres for bigger rims, so people go with brands like "Wanli" which are simply horrible.

I agree - its all about unsprung mass. People would be surprised to learn how much some of these big rims weigh.

[Casablanca]

i like my 18" mags they look good and they are plenty wider than stock im running 265/45 rear and 255/40 front this is for the skyline.

never had a problem i run federal 595s on both front and rear so they arent really that much more expensive.

[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.

[xbgs351]

Originally Posted by JC

That's true - his base assumption is that when you go for a larger rim size, you keep the same profile tyre, thus giving a larger overall circumference. That would be both stupid and illegal. When you go for a larger RIM size, you actually go for a lower profile tyre (and he does touch on the effects of that later, so who knows what he's thinking in points 1 to 4), which results in the same (or very similar) rolling diameter and circumference.

Yes, the weight of the wheel may be an issue in terms of momentum, but it's not like a 19" wheel is twice as heavy as a 17" - there'd be a couple of KGs per wheel in it, and you can get that just between different brands of the same size anyway.

Mazda6person hasn't really thought about what he is saying, or has only thought enough about each point, but not looking at the whole picture (or wheel).

Ever heard of Moment of Inertia or unsprung mass?

[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.

[Dazza XLT]

I find a lot of local people around here spend far too much on large rims, and no-where near enough on fitting decent rubber.

It won't look fully sick after you lose control in the wet and smash into a kerb, because you skimped and bought crap tyres!

Personally I'd rather stick to a 16"/17"/18" rim with a decent brand of tyres.

Cheers

Darran

[Casablanca]

unfortunately i have to agree with the post above^^^

it also depends on what kind of use your putting them to.

[Mr Cube]

Originally Posted by Disciple

Going to larger rims almost certainly means lower profile tyres which in turns gives rubbish ride quality. Most of the time you can't even buy decent brand tyres for bigger rims, so people go with brands like "Wanli" which are simply horrible.

I run 19" on XR6 Falcon, with Koni shocks, King Super lows set up correctly the ride quality is a firmer then stock but still comfy.. I also manage to get good tyres each time, I even had the offer of Pirelli's so I think a lot of the tyre companies are definatly making them.

I did upgrade my brakes from AUI to BA as I did notice a degrade in braking, with the stock calipers, but good pads and slotted rotors. Upgraded to BA size calipers and rotors and is is much better.

My choice was purely looks, not on track performance.

[MITCHAY]

Originally Posted by Disciple

Anything bigger than 19" in my book is stupid. I think 18's are the perfect size, hence why you see proper Japanese fast cars (Skylines, Supras, EVOs etc) all run 17" and 18" rims. It's all to do with unsprung mass in terms of performance. Reduce the unpsrung mass means better braking, better acceleration, cornering etc. IMO, 20's on a normal sedan or whatever look retarded and only serve to make the car owner look like a complete tool who knows nothing about car dynamics. Going to larger rims almost certainly means lower profile tyres which in turns gives rubbish ride quality. Most of the time you can't even buy decent brand tyres for bigger rims, so people go with brands like "Wanli" which are simply horrible.

X2 I have heard that removing 1kg of unsprung mass equals about 4kg from the car. Something along those lines. Not a big fan of massive wheels anyway. I'd only go to 18" on my car if I were to upgrade at a max.

Wouldn't mind throwing some Prodrives, Work or Rays/Volk on my car but they are expensive :

[dishpig]

All I know is when I get bigger rims I'm keeping my 17's for the track, doesn't seem right taking 19's on a track.

[tex]

My experience after many track day events is that there is NO performance gain to be had in swapping from 17 - 18' wheels on the circuit.

I had both sizes with the same tires (in the different diameter) on the car on the same day on the same track. six laps with 18's, a dozen laps with 17's.

It was not a perfect test, as the 17's had wider tires (255 compared with 245)
but the results were conclusive.

There was bugger all in it, not enough to get a difinitive better or worse result. If there's not an 'improvement' on the track, there aint no way you'll see one on the street.

Bling effect only. And 20's on street cars - ha ha, especially when they fit those piddly little 235 or 245's........ which I reckon is way out of proportion to the wheel diameter. Fit 'em up with a 285 or 295 and then we're getting serious.