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i plan on putting 18inch wheels on a 2000 323i but i recently heard that if i put 18's on the car that it messes up the whole perfoprmance of the car and that i should get 17 inch wheels i want to put new wheels on the car and yet still get the same performance and handling out the car as if it was stock so should i go for the 17's or the 18's
feel free to post up some pics if u want to
 

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I have 18i's on my car, and I do feel a differance when I put back the stock rims which are 16's. The ride feels rougher with the 18's.
 

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I've had both 17" summer tires and 18" summer tires on my car, and I can tell you from the seat of the pants there's not much difference at all, either in ride or handling.

However, the 17s are probably ideal from a performance standpoint, giving you all the handling you really need, with lower weight and less inertia than an 18" wheel.

I prefer 18s, because I prefer the looks and that last tenth of a second in an autocross just doesn't mean that much to me.
 

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Jayhawk
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A rule of thumb that I have heard is that for every 1-inch increase in wheel diameter (for same model wheel), you lose effectively 10hp at the ground due to inertia. I have 18X8.5 inch SSR comps for street use and use 17X8.5 SSR Comps for DE and autocross events. I can feel a difference in power (should also be a difference braking).

With that said the difference is minor on the my 330i but you may feel more of a difference with the lower hp 323. I did not feel much difference when I put 17's on my 323 but 18 may have made a noticeable difference.

Regarding turning, the lower the profile, the better the turn-in and response will be.
18:


17 inch
 

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Protect your (lug) nuts
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17 or 18 foot wheels? thats pretty big, if you ask me ;)
 

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1.888.JLEVISW
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The only issue you run with bigger wheels (assuming they are sized appropriately) is weight. Wheels are just one part of your car's unsprung weight and when you increase this value, the effect on your car's acceleration is magnified. I believe the ratio is 1lb unsprung = 10lbs sprung weight. The reason being the engine has to rotate this mass which requires a lot more energey expenditure than just pulling added weight.

As a result, you will see most people go for forged or lightweight wheels which diminishes the amount of drag caused by increased unsprung weight. Likewise, many people choose light wheels such as OZ's which actually DECREASE unsprung weight and IMPROVE performance.

In short, it's important to consider weight when choosing a bigger wheel. Other than that, the general consensus is wider is better as you put more rubber to the ground and increase grip thus improving handling.

We have a wide range of wheel upgrades available from BBS and custom DPE wheels to Velocity Motoring CSL wheels, Luff D1 (BBS LM Style), and MRR designed wheels.

Email or call in for a pricing quote :)
 

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KU Ned said:
A rule of thumb that I have heard is that for every 1-inch increase in wheel diameter (for same model wheel), you lose effectively 10hp at the ground due to inertia. I have 18X8.5 inch SSR comps for street use and use 17X8.5 SSR Comps for DE and autocross events. I can feel a difference in power (should also be a difference braking).

With that said the difference is minor on the my 330i but you may feel more of a difference with the lower hp 323. I did not feel much difference when I put 17's on my 323 but 18 may have made a noticeable difference.

Regarding turning, the lower the profile, the better the turn-in and response will be.
18:


17 inch
Thanks for the pictures. That's the best comparision by looks I've seen. The 18's look so much better, while being on the edge of pratical depending on the pavement in your area. I love my type 71 18's for looks, but I'm also considering 17" SSR Comps for track rims.
 

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As Jlevi pointed out for all you guys who have 18" rims and above on their BMW`s,may think its really cool but you are literally decreasing the performance,fuel economy big time and putting unneccessary stress on all components linking to the wheel from engine shaft to all the suspension system etc.As cool as it may look,you are decreasing the longevity of the whole car.
Go with 17" or light weight 18"alloys like 5ZIEGEN and other hitech companies that provide light wheel option.
 

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coolandmellow said:
As Jlevi pointed out for all you guys who have 18" rims and above on their BMW`s,may think its really cool but you are literally decreasing the performance,fuel economy big time and putting unneccessary stress on all components linking to the wheel from engine shaft to all the suspension system etc.As cool as it may look,you are decreasing the longevity of the whole car.
Go with 17" or light weight 18"alloys like 5ZIEGEN and other hitech companies that provide light wheel option.
You make it sound like you're destroying your car by putting 18inch rims on.... ZHP's come standard with 18's and it's a factory option for 330's.......
 

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It's not just a matter of the weight, it's also where the weight is.
The closer to the center the better. Something else to consider, on the ZHP, where the engine is more powerful then the 323, the net effect will probably be less.
But regardless, less unsprung weight = better suspension performance. Less rotational mass and the closer to the center of the hub = better acceleration/deceleration performance.
 

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snewcrash said:
You make it sound like you're destroying your car by putting 18inch rims on.... ZHP's come standard with 18's and it's a factory option for 330's.......
I agree you won't be destroying the car.
The 18" in the ZHP is fitted to the sports suspension (different tunning), which the OP probably doesn't have.
 

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1.888.JLEVISW
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coolandmellow said:
As Jlevi pointed out for all you guys who have 18" rims and above on their BMW`s,may think its really cool but you are literally decreasing the performance,fuel economy big time and putting unneccessary stress on all components linking to the wheel from engine shaft to all the suspension system etc.As cool as it may look,you are decreasing the longevity of the whole car.
Go with 17" or light weight 18"alloys like 5ZIEGEN and other hitech companies that provide light wheel option.
I was in no way saying that 18s will destroy your car's performance. I was simply pointing out the fact that generally when you increase wheel size, you increase weight.

With that said, we provide a wide variety of wheel options (in 17, 18 and 19 inches) that are LIGHTER than stock and with an overall LARGER diameter :)
 

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coolandmellow said:
As Jlevi pointed out for all you guys who have 18" rims and above on their BMW`s,may think its really cool but you are literally decreasing the performance,fuel economy big time and putting unneccessary stress on all components linking to the wheel from engine shaft to all the suspension system etc.As cool as it may look,you are decreasing the longevity of the whole car.
Go with 17" or light weight 18"alloys like 5ZIEGEN and other hitech companies that provide light wheel option.
I'll admit I choose 18" wheels for looks, but I think your statement is a tad dramatic, especially for a factory option wheel like mine.

Fuel economy in the city would be affected, but not big time. Fuel economy on the highway should remain roughly constant as the weight difference is insignifcant once rolling (except for ride/handling). Its not like we're putting 33" truck tires on the car.

There is one benefit of 18" wheels that you didn't mention, and then is potentially better turn-in feel due to the shorter sidewall.

As far as longevity of the whole car, I disagree. Shocks and brakes may wear out slightly (although probably not measureably) faster but they are consumables anyways. Its also not going to affect clutch life or any other drivetrain parts because the difference is too small. There's a greater difference between how people drive and how many passengers they carry.
 

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You also need to take the weight of the tire into consideration. When I changed my wheels from M68's to M72's, I paid close attention to the weight of the tires I was putting on the new wheels. The M72's weigh almost exactly the same as the M68's, but I bought a tire (Yoko AVS ES100's) that weight somewhere around 2-3 lbs LESS than the 17" ones that were on there before. So that's reducing even more unsprung weight, AND it's the furthest away from the center of the wheel as you can get. The result was my car not only had more grip, but actually did feel lighter and accelerated better.
 

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ilkhan4 said:
AND it's the furthest away from the center of the wheel as you can get. The result was my car not only had more grip, but actually did feel lighter and accelerated better.
You do know that moving the weight OUT reduces power, right? The farther away from the center, the more rotational inertia.

On SportsCar Revolution, they took a stock RSX. Went from stock 16" rims to LIGHTER 18" rims.. and also added big brakes w/ bigger rotors. Lost 12hp on the dyno.
 

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snewcrash said:
You make it sound like you're destroying your car by putting 18inch rims on.... ZHP's come standard with 18's and it's a factory option for 330's.......
not destroying but a lot of things on the zhp is also for looks and not maximizing performance. the reason why big rims are used is to fit in bigger brakes. but if 17" rims already suffice for the brakes that you already have, you don't need bigger rims.
 

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HW said:
not destroying but a lot of things on the zhp is also for looks and not maximizing performance. the reason why big rims are used is to fit in bigger brakes. but if 17" rims already suffice for the brakes that you already have, you don't need bigger rims.
Exactly.
Every single thing that's done to a race car is done for a functional purpose. For example, bigger wheels (to accommodate big brakes), spoilers (for high speed stability), lower chassis (to lower center of gravity and aerodynamics), etc.
Novices/posers try to imitate a particular race car look, without knowing the purpose behind. For example, I laugh when I see Hondas with 18" wheels emphasizing the tiny wimpy brake rotors. Or how about a staggered wider rear tire in a Civic? :rofl:
People put enormous double decker wings on riced out cars that can't go faster than 60mph. It's just adding dead weight. And worse, those wings don't even have the right aerodynamic shape.
Invariably, the riced out cars with custom fiberglass kits have their bumpers or fenders cracked because the car is too low for city applications. :rofl:
 

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yep, if it wasn't for the big brake disks, we could get away with having small diameter wheels make them wider to compensate for the larger tire patch. the small diameter wheels will lower the car as well.

Boile said:
Exactly.
Every single thing that's done to a race car is done for a functional purpose. For example, bigger wheels (to accommodate big brakes), spoilers (for high speed stability), lower chassis (to lower center of gravity and aerodynamics), etc.
Novices/posers try to imitate a particular race car look, without knowing the purpose behind. For example, I laugh when I see Hondas with 18" wheels emphasizing the tiny wimpy brake rotors. Or how about a staggered wider rear tire in a Civic? :rofl:
People put enormous double decker wings on riced out cars that can't go faster than 60mph. It's just adding dead weight. And worse, those wings don't even have the right aerodynamic shape.
Invariably, the riced out cars with custom fiberglass kits have their bumpers or fenders cracked because the car is too low for city applications. :rofl:
 
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