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View Full Version : 245 front, 255 rear -- anyone?


thenobot
05-17-2005, 09:38 AM
(first post here)

I did a couple of searches, but couldn't find anything referring to what I'm thinking of doing.

Currently, I'm driving a 98 M3/4 with 245/40s all around on 17x9 BBS RGR. The difference in handling between this and the stock staggered setup is, well, staggering! Bye bye understeer.

I'll be receiving a new 05 M3 ZCP in a couple of weeks, and am concerned about the level of stagger they've put on the car (225 front, 255 rear), especially since now I know what switching fron staggered to non-staggered does for the car. I'm guessing that there will be a fair amount of understeer in a neutral cornering attitude.

I see posts mentioning 245 front, 275 rear, but I'd like to get the tires as close to the same size as possible.

I'd like to keep the gorgeous ZCP wheels, but at the same time dial out as much understeer as possible. I see two options:
1) Run a 245 tire up front. 245/35 is taller than stock, 245/30 is shorter. Which way should I go?
2) Buy a pair of ZCP rear wheels from BMW or Turner and put them on the front. Will these even fit? I'm guessing I'll at least need a spacer. I'd rather not roll the fenders (trying to keep this car as stock as possible!)

Anyone do something similar or have any experienced advice?

Thanks!

RChoudry
05-17-2005, 11:04 AM
I'm interested in this as well. I'd like to keep the stock 18 inchers for now and upgrade the front skinny tires. Turn-in and on center feel is horrible while the car handles okay overall.

Camber negativity is a great way to go, but I'm interested in wider fronts with stock rears in the 18 inch set-up.

Nick325xiT 5spd
05-17-2005, 11:07 AM
Rear wheels will only fit up front if you've got a ****load of camber. The problem is that the rear wheels are not only wider, but they've already got what is effectively a 20mm spacer on them. If you've got 3.5-4 degrees of negative camber, rears will work great. Forget it, otherwise.

The best way to fix the understeer would be with a set of camber plates. I believe that GC has a set that will work with the stock springs.

thenobot
05-17-2005, 11:35 AM
The best way to fix the understeer would be with a set of camber plates. I believe that GC has a set that will work with the stock springs.

Nick -- just so I'm clear -- are you saying that adding negative camber to the front is better than adding more rubber to the front?

Can you explain this a little more? My brain has put this into its "does not compute" folder :)

Thanks.

thenobot
05-17-2005, 11:37 AM
Anyone running 245 front with 255 rear? If I keep 255s in the back, should I get 245/35 or 245/30? (on 19" wheels)

Nick325xiT 5spd
05-17-2005, 11:51 AM
It's very simple, the M3's suspension (like all BMWs) works so that you end up LOSING camber as the body rolls. When you're cornering hard, the tire actually ends upon the outside edge, or even on the sidewall. Sure, more rubber is good, but you're getting a very limited use of it that way.

I actually run about 4 degrees of negative camber up front. That's what it took (combined with a MUCH stiffer suspension) to keep the front tires in full contact with the pavement. And that's 285/30-18 all around, by the way. My normal street tires are 275/35-18 all around.

http://teamwtf.org/gallery/albums/album22/pics_046.sized.jpg

As for tire sizes, 245/35, and that's a perfectly acceptable size for the front.

thenobot
05-17-2005, 12:14 PM
Thanks Nick.

Did you have to do anything special for the front to run such wide wheels/tires? Spacer, rolled fenders, etc.?

Nick325xiT 5spd
05-17-2005, 12:22 PM
Thanks Nick.

Did you have to do anything special for the front to run such wide wheels/tires? Spacer, rolled fenders, etc.?
In order to run with coilovers, or with rear wheels, you need 3.5-4 degrees of negative camber.

With wheels that have a less aggressive offset, and the stock suspension, the tire will actually go UNDER the spring perch so you'll have lots of clearance.

Do you understand the relationship between camber, offset (spacers change offset), and fender clearance?

bren
05-17-2005, 12:28 PM
Not that Nick's advice isn't valid but it should be made clear that what he is suggesting is for autox/track. Running that much negative camber on the street will most definitely wear tires down quickly.

Nick325xiT 5spd
05-17-2005, 12:30 PM
Not that Nick's advice isn't valid but it should be made clear that what he is suggesting is for autox/track. Running that much negative camber on the street will most definitely wear tires down quickly.
If you want to run rear wheels up front... Or if you actually want to attack the understeer problem, you need camber. Wider tires won't do much.

thenobot
05-17-2005, 12:33 PM
Do you understand the relationship between camber, offset (spacers change offset), and fender clearance?

yes. just not the parameters of these adjustments/parts/attributes on an E46. I've done quite a bit of work on E36s, so I'm being cautious with this new car, since there are new parameters to learn.

bren
05-17-2005, 12:36 PM
If you want to run rear wheels up front... Or if you actually want to attack the understeer problem, you need camber. Wider tires won't do much.
Well, wider tires are better than narrow tires....especially if he's only worried about street driving.

And, it's not that I disagree with you....just wanted to point out that the extra neg. camber does have side effects.

Pinecone
05-17-2005, 06:30 PM
Not that Nick's advice isn't valid but it should be made clear that what he is suggesting is for autox/track. Running that much negative camber on the street will most definitely wear tires down quickly.

Only if your toe is off. :) Heck you are running some 2.5 - 3 degrees yourself. :)

The choice I made with a set of street tires for track use was 245 front, 265 rear on stock wheels. Worked nicely.

Pinecone
05-17-2005, 06:32 PM
yes. just not the parameters of these adjustments/parts/attributes on an E46. I've done quite a bit of work on E36s, so I'm being cautious with this new car, since there are new parameters to learn.

Actually pretty easy with an E46 M3. Up pop the strut bar mounts off, and pull the little pin and you gain about 0.5 degrees of negative camber. Swap the strut hats from left to right, and you end up in teh 2.5 - 3.0 range depending on your car.

FlyingDutchMan
05-22-2005, 11:59 PM
I know up to 275's on 10 inch rims will fit up front with no mods other than some negative camber at about -1.5 - 2.5

This picture below is 275 Hoosiers on my 18x9.5 CCW Race Classics.

AleksT
06-30-2006, 12:41 PM
Actually pretty easy with an E46 M3. Up pop the strut bar mounts off, and pull the little pin and you gain about 0.5 degrees of negative camber. Swap the strut hats from left to right, and you end up in teh 2.5 - 3.0 range depending on your car.


I've never done this before but it sounds very easy. Is it really that simple? Do you have to have the wheels off the ground (unloaded suspension) to do this? DO you have to put the pins back in after it moves? Or do you leave it out? W/out the pin won't they struts move around?

Thanks for answering and sorry if the questions sound stupid but I've never seen this done before. It may make more sense when I'm actually doing it.

///M3lissa
06-30-2006, 12:59 PM
I've never done this before but it sounds very easy. Is it really that simple? Do you have to have the wheels off the ground (unloaded suspension) to do this? DO you have to put the pins back in after it moves? Or do you leave it out? W/out the pin won't they struts move around?

Thanks for answering and sorry if the questions sound stupid but I've never seen this done before. It may make more sense when I'm actually doing it.

Its really simple.

Edit: Here is the DIY: http://m3.madrussian.net/diy_camber.shtml

AleksT
06-30-2006, 03:10 PM
Thanks! Everything I learn about my M3, I learn from ///M3Lissa

LMC
06-30-2006, 10:42 PM
I'm running 245 front and 255 rear, but in 18-inch: 245/40R-18 front and 255/40R-18 rear PS2s.

///M3lissa
06-30-2006, 11:20 PM
Thanks! Everything I learn about my M3, I learn from ///M3Lissa

Aweeee..thanks :) I guess I've learned something in the year + I've been here :D