Crazy question for you lucky m3 owners

Okay i realized more and more i read that most m3 owners are going towards the 18' rims rather than the 19's!!

i mean of course there is two big 20' m3 rims owners should shoot themselves but at the same time, what exactly is the reason behind choosing 18 9.5 over 19 9.5??

advantage and disadvantages ?

is it just taste?

does the m3 have a harder time breaking the rear end loose with 19?

*not a m3 owner so cant really experiment myself*

Originally Posted by cyberlando

does the m3 have a harder time breaking the rear end loose with 19?

*not a m3 owner so cant really experiment myself*

youre asking for the wrong reason

go google unsprung weight

Originally Posted by Drewdown

go google unsprung weight

lol, I can bet that only 5% of M3 owners know what that is

Originally Posted by Blocked Out

lol, I can bet that only 5% of M3 owners know what that is

I sure as hell hope not

Originally Posted by Drewdown

youre asking for the wrong reason

go google unsprung weight

woww good info broo, i will admitt that i never heard of this before!!

but if that is the case why does the m3 csl the competition level m3 with all its glory Come with 19's??

Originally Posted by cyberlando

woww good info broo, i will admitt that i never heard of this before!!

but if that is the case why does the M3 CSL the competition level M3 with all its glory Come with 19's??

the CSL wheels are some of the lightest wheels on a production car. they are not light by lightweight aftermarket wheel standards but for production cars yes. they are made by BBS and BMW publishes they save a combined total of 24.2lbs at all corners over the non-csl 19" wheels. the Michelin Pilot Sport Cup tires used are also very light. another reason they cost so much.

Ride quality improves (more sidewall), weight goes down (smaller wheel), and the potential to bend a wheel goes down as well. Tires are also cheaper.

Originally Posted by LittleChrist12

Ride quality improves (more sidewall), weight goes down (smaller wheel), and the potential to bend a wheel goes down as well. Tires are also cheaper.

Yep.. what he said..

Personal choice on looks is is number 1, then its about cost , then reliability .

The diameter and width of the rim or tire has nothing to do with breaking the rear end loose . Even weight was no relationship with size

Originally Posted by Blocked Out

The diameter and width of the rim or tire has nothing to do with breaking the rear end loose .

I'm not sure I can completely agree with this. "moment of inertia" suggests differently.
And a wider tire and rim certainly can aide in traction. Where a thinner W&T might start to somewhat break traction, a wider combo would hold at the thresehold.

Originally Posted by Alex323Ci

I'm not sure I can completely agree with this. "moment of inertia" suggests differently.
And a wider tire and rim certainly can aide in traction. Where a thinner W&T might start to somewhat break traction, a wider combo would hold at the thresehold.

Moment of inertia sure does play a role but a light wheel can be just as stable as a heavier one as long as it paired with good tires . Another thing you cant forget is tire compound .

Here is a question for you, which wheel tire combo will have more traction ?

LTW5 17x8.5" Mounted with Hoosier A6 225/45ZR17

or

OEM CSL rims mounted with Michelin PS2 275/35ZR19

The reason why wider wheels/tires help cars NOT break traction is because they're often way too heavy and the car simply doesnt make that much power to break them loose. Thats why people often find that their car became slower after they put some gangsta rims on it

Look at it this way , cars that race in Touring Car Championships Series have 235 tires and they keep pretty stable on the track and on this forum most people have 275 tires mounted on the biggest rims you can find and they can barely keep out of the ditch

Originally Posted by Blocked Out

The diameter and width of the rim or tire has nothing to do with breaking the rear end loose . Even weight was no relationship with size

Originally Posted by Blocked Out

Moment of inertia sure does play a role but a light wheel can be just as stable as a heavier one as long as it paired with good tires . Another thing you cant forget is tire compound .

The reason why wider wheels/tires help cars NOT break traction is because they're often way too heavy and the car simply doesnt make that much power to break them loose.

Yes I totally agree that the tire/compound has plenty to do with it. But I was only saying I can't agree with your statement, "diameter and width has nothing to do with breaking the rear end loose". I absolutely believe it does. Two exact same model tires and at the onset that the smaller width wheel starts to lose traction in most every circumstance the wider wheel will have traction and it's onset to lose traction will be later on. Thus width and contact patch is a factor.

Originally Posted by Alex323Ci

Yes I totally agree that the tire/compound has plenty to do with it. But I was only saying I can't agree with your statement, "diameter and width has nothing to do with breaking the rear end loose". I absolutely believe it does. Two exact same model tires and at the onset that the smaller width wheel starts to lose traction in most every circumstance the wider wheel will have traction and it's onset to lose traction will be later on. Thus width and contact patch is a factor.

Well,if you put it this way then yes size and width does affect "breaking the rear loose" . If you compare same model rims and tires then the bigger rims paired with wider tires will make breaking the tires loose more difficult .

I was just focusing on the fact that you can get skinnier tires that are more sticky/stable then some wider tires, therefore there is no direct correlation with width and stability (breaking rear end loose). Yes you can use 2 sets of same brand/model as data to prove me wrong but when we talk tires, we need to take all kinds of tires into account .

Come on, you know what I mean

Smaller means greater acceleration too. If the two wheels, 18 and 19 weigh the same, the smaller diameter of the 18s is, in effect, the final gear. You'd have greater acceleration, though a slightly lower potential top speed.

If I raced an identical car to mine with 17s, I'd win...coz I'm on 16s. Also, the more weight you have further from the axle, the more power it takes to move it...or something like that. I didn't take physics, but I did stay at a Holiday Inn once!

Originally Posted by dmax

Smaller means greater acceleration too. If the two wheels, 18 and 19 weigh the same, the smaller diameter of the 18s is, in effect, the final gear. You'd have greater acceleration, though a slightly lower potential top speed.

If I raced an identical car to mine with 17s, I'd win...coz I'm on 16s. Also, the more weight you have further from the axle, the more power it takes to move it...or something like that. I didn't take physics, but I did stay at a Holiday Inn once!

Doug, the smaller rim diameter is accommodated by higher sidewall on the tire. Regardless if you have 15s 16s or 18" rims, your overall diameter is still identical , which is 25" for E46 Non-M . For non-M E46 wheel tire combo must be 25" +/-2%.

For M3s the overall height is 26" +/-2%

Also, there are 20" rims that weigh less then 18" rims, and some 17" rims that weight more then 19" rims , see where Im going here ? You cant just say because this rim is bigger it automatically weights more then a smaller one .

Originally Posted by dmax

Smaller means greater acceleration too. If the two wheels, 18 and 19 weigh the same, the smaller diameter of the 18s is, in effect, the final gear. You'd have greater acceleration, though a slightly lower potential top speed.

If I raced an identical car to mine with 17s, I'd win...coz I'm on 16s. Also, the more weight you have further from the axle, the more power it takes to move it...or something like that. I didn't take physics, but I did stay at a Holiday Inn once!

Usually the overall diameter of the wheel stays the same because a smaller rim demands a larger sidewall. But, I do agree that the larger rim will add more mass away from the axis of rotation which will hinder performance.

Edit: Damn, Blocked Out beat me to it!

One way to understand how two rims with the same weight but different diamaters would affect performance is to take a "thing" and tie a string to it. Then twirl it around in a big circle and then smaller diamater circles. The different forces you need to get the same rpm is what your car has to deal with.
The CSL has 19's....because it can.

Originally Posted by HiHoBrian

The CSL has 19's....because it can.

thats not helping at all

so over all the diameter needs to be the same, but for weight saving and performance reason you'd rather have more rubber than metal? since rubber is lighter

is that about right