# R Comp Traction (in straight line acceleration)



## SLang (Dec 1, 2003)

I guess I made certain assumptions that his tires are fresh and are the correct size for his wheels? :dunno: I don't autocross. Maybe you could enlighten us?


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## SoloII///M (May 16, 2003)

SLang said:


> I guess I made certain assumptions that his tires are fresh and are the correct size for his wheels? :dunno: I don't autocross. Maybe you could enlighten us?


 

This thread is WAY below him...


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## TeamM3 (Dec 24, 2002)

SoloII///M said:


> This thread is WAY below him...


no, I just learned not to wear a petty ego on my shirtsleeve  maybe you should try it some time, you just might learn something along the way :dunno: the difference between us is when it comes to picking up things that can be a benefit to me the last thing I'm thinking of is my personal feelings :thumbdwn:

I could go work for a guy like AJ Foyt and not give a second thought to his temper tantrums and a guy like you wouldn't last through the first day . It's only personal if you let it be, so quit blaming people like me because you're not man enough to know your own self-worth regardless of what anyone else thinks or says. I'll give Andy credit for picking up on this in months when many forum members haven't come to grips with it in years :tsk: there's no doubt in my mind that he'll surpass you in both driving and setup skill in short order as a result

sure, I could just spit it out and tell you what I think it is, but then that doesn't encourage any critical thinking on your part, and it's critical thinking process that keeps from falling for the fallacy of generalizations and assumptions. In summary, I'm not really making fun of you, I'm trying to get you to use your mind and think the situation through, but people with the little girl mentality aren't going to make it that far - are they -

here's a hint, regardless of how low Andy drops his tire pressure, the 265 rear tires will still wear in the center

I'd also be interested to know how much of the inside treadwidth on the front 265 tires doesn't even show any wear ...


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## SoloII///M (May 16, 2003)

TeamZ4 said:


> no, I just learned not to wear a petty ego on my shirtsleeve  maybe you should try it some time, you just might learn something along the way :dunno: the difference between us is when it comes to picking up things that can be a benefit to me the last thing I'm thinking of is my personal feelings :thumbdwn:
> 
> blah blah blah blah typical Mark Sipe whining blah blah blah
> 
> ...


What was that you said about inane BS? :eeps: :rofl:


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## TGray5 (Jan 22, 2002)

c'mon people, let's avoid the insults and personal attacks. We're all enthusiasts enjoying our cars and trying to learn from each other.


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## SLang (Dec 1, 2003)

Wow.....must be history here some of us aren't privvy to.....


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## Andy (Jul 16, 2003)

StahlGrauM3 said:


> c'mon people, let's avoid the insults and personal attacks. We're all enthusiasts enjoying our cars and trying to learn from each other.


 :stupid:

Mark (TeamZ4), you have a lot of experience in regards to autocross and car/wheel/tire setup. However, I am baffled by the way you go about sharing your knowledge with the online community. A lot of us are here to learn (I for one), you make it quite difficult to learn anything from you. Maybe that's what you want&#8230;you don't want to share your secrets. Personally, I'm convinced that's the case, which is fine, nothing wrong with that. However, if that's not the case, and you don't mind sharing what you've learned over the years, could you please stop speaking in riddles so I (we) can learn something from you? Thank you.



TeamZ4 said:


> here's a hint, regardless of how low Andy drops his tire pressure, the 265 rear tires will still wear in the center
> 
> I'd also be interested to know how much of the inside tread width on the front 265 tires doesn't even show any wear ...


Just so everyone knows... I am running 265/35/18s up front on 18x8 wheels and 265/35/18s in the rear on 18x8.5 wheels. I am 1" outside of the recommended wheel width range on the front wheels and 0.5" outside of the recommended wheel width range on the rear wheels.

I have approx. 50 runs on these tires (this includes the Evolution school I attended back in March) that I purchased shaven and heat cycled from TireRack.

Most of the wear on the rear tires is in the middle, with the second most wear on the outside edge. Here is a picture of one of my rear tires (they both pretty much look the same).










Most (if not all) of the wear on the front tires is from the middle of the tire to the outside edge, with extensive wear on the outer edge. Here is a picture of one of my front tires (they both pretty much look the same). Two weeks ago I had the front tires flipped over so I can utilize the other side of the tire (10 runs have been made since the tires were flipped). I am sure a lot of this has to due with the lack of camber I can set up front (I'm currently maxed out at -1.5 up front and -2 in the rear).


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## GregD (Feb 5, 2003)

Andy,

Did you mark the outside edge on your rear tire photo backwards? Looking at the wearbars it's pretty obvious that what you have marked as the outside edge has less wear than the other side.
:dunno:


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## SoloII///M (May 16, 2003)

GregD said:


> Andy,
> 
> Did you mark the outside edge on your rear tire photo backwards? Looking at the wearbars it's pretty obvious that what you have marked as the outside edge has less wear than the other side.
> :dunno:


Maybe he's running more rear (-) camber than stock.

Similar wear pattern to Ken's car, running the same tires on his '03 M3. I believe the wheel widths are the same though the rears may be 9" wide. :dunno

Incidentally, the top-finishing E46 M3 at the DC National Tour last year did quite well for himself running these tires on stock wheels. I relalize it may not be the 100% optimal setup, but in lieu of purchasing four $250 Hoosiers it seems to work "OK" for local competition.

Andres and Carlos are really nice, helpful guys and they sent Ken a bunch of e-mail about how they came to run these tires, what pressures, temperatures, etc. they were running. Shoot him an e-mail and he can forward the info to you.

John


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## Andy (Jul 16, 2003)

GregD said:


> Andy,
> 
> Did you mark the outside edge on your rear tire photo backwards? Looking at the wearbars it's pretty obvious that what you have marked as the outside edge has less wear than the other side.
> :dunno:


Greg, that is a good observation that I did not notice at first. I do have the outside edge marked correctly. You'll notice that the very outside edge tread has more wear then the very inside edge tread. John is right, I am running more negative camber in the rear (-2 degrees) which I think is why I have more wear toward the inner middle section of the tire. Seeing this, I may want to add a little more positive camber to -1 degree and see if I can't get more even tire wear in the rear... this could even have something to do with less grip on acceleration.

What do you guys think? Should go from -2 to -1 degrees in the rear? :dunno:


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## SoloII///M (May 16, 2003)

Andy said:


> Greg, that is a good observation that I did not notice at first. I do have the outside edge marked correctly. You'll notice that the very outside edge tread has more wear then the very inside edge tread. John is right, I am running more negative camber in the rear (-2 degrees) which I think is why I have more wear toward the inner middle section of the tire. Seeing this, I may want to add a little more positive camber to -1 degree and see if I can't get more even tire wear in the rear... this could even have something to do with less grip on acceleration.
> 
> What do you guys think? Should go from -2 to -1 degrees in the rear? :dunno:


Depends on how you think the car is coming out of corners. I went to more negative rear camber this year (-1 degrees to -1.5 degrees) because I wasn't able to put power down as early as I wanted last year - there was not enough lateral rear grip. My wear is even across the tread face. Will try to get pics at the event this weekend.

Looks to me like you're running too much rear camber for the body roll your car is exhibiting but it's hard to tell without driving it...


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## GregD (Feb 5, 2003)

Andy said:


> Greg, that is a good observation that I did not notice at first. I do have the outside edge marked correctly. You'll notice that the very outside edge tread has more wear then the very inside edge tread. John is right, I am running more negative camber in the rear (-2 degrees) which I think is why I have more wear toward the inner middle section of the tire. Seeing this, I may want to add a little more positive camber to -1 degree and see if I can't get more even tire wear in the rear... this could even have something to do with less grip on acceleration.
> 
> What do you guys think? Should go from -2 to -1 degrees in the rear? :dunno:


Looking at your wear pattern, I would. Or maybe -1.5. I've never been a big fan of a lot of camber in the rear as long as the rear suspension design has enough camber gain to compensate for the car's roll. I'm not sure about a 3 series, but I would hope that with a modern multi-link design, the BMW engineers would have done a good job on this.

Less camber will help acceleration, and even more importantly, braking. It looks like your outer edges are rolling under, which usually means you need more air. Hope you're keeping a log of what changes you make and what impact they have on the car.


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## SLang (Dec 1, 2003)

At the risk of asking a silly question, why are you running tires that are technically too wde for your wheels? Even at the correct air pressure, if you're still wearing the center of the tread out, doesn't that mean you're not getting an optimal contact patch? Would you be better off running an narrower tire, or getting a wider wheel?


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## Andy (Jul 16, 2003)

SLang said:


> At the risk of asking a silly question, why are you running tires that are technically too wde for your wheels? Even at the correct air pressure, if you're still wearing the center of the tread out, doesn't that mean you're not getting an optimal contact patch? Would you be better off running an narrower tire, or getting a wider wheel?


With this set of tires, I was really just wanting to experiment with how much rubber I could fit under the car. For my next set of tires I was thinking of going with the 245/35/18 Hoosier A3S04s, the rears would be ok, however I would be 0.5" outside of the recommended wheel width range on the front wheels.

If I actually wanted to get a tire that would properly fit the wheel I would have to go all the way down to a 225 wide tire (the Hoosier A3S03).

So I guess my question is this...

Which tire would have more grip (for autocross), the 245/35/18 Hoosier A3S04s all the way around (that fits the rears properly but is .5" too wide for the fronts) or the 225/40/18 Hoosier A3S03s all the way around (that fits both front and rears properly)?

EDIT : By the way, I need to stick with the same size wheels in order to remain in the stock class.


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## SoloII///M (May 16, 2003)

Andy said:


> EDIT : By the way, I need to stick with the same size wheels in order to remain in the stock class.


... and hence part of the difficulty of running stock - sometimes "less than optimal" setups work OK, at least locally. Like I said, Carlos and Andres had good results at the DC Tour with their E46 M3 running the same setup.

Andy, if you look at how a Hoosier is constructed, the sidewall is pushed out from the bead surface of the rim. I believe this is why a "225" hoosier is as wide as a "245-255" street tire.

The 225 Hoosier would be the way to go for best results, I suspect.


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## GregD (Feb 5, 2003)

Andy said:


> With this set of tires, I was really just wanting to experiment with how much rubber I could fit under the car. For my next set of tires I was thinking of going with the 245/35/18 Hoosier A3S04s, the rears would be ok, however I would be 0.5" outside of the recommended wheel width range on the front wheels.
> 
> If I actually wanted to get a tire that would properly fit the wheel I would have to go all the way down to a 225 wide tire (the Hoosier A3S03).
> 
> ...


Maybe it's a typo on Tirerack's web site, but they show the measured rim width for the 245/35-18 as 8". A lot of the R tires are designed to work on smaller than normal rim widths. :dunno:

I think 225s would actually work a little better on the car for overall grip and good recovery characteristics, but I'd still go with the 245s for the slightly shorter tire. A slightly lower center of gravity and a little lower overall gear ratio I think will be noticeable. Especially since the 225/40-18 are special order on the 03 tire, and not currently available in the 04 tire.


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## ·clyde· (Dec 26, 2001)

Remember that the section width is not the tread width. The section width is supposed to be the widest point between the two sidewalls when mounted on the reference size wheel (or something like that).

IIRC, DOT specifices what size wheel to use with what section width tires, and 8" is what is to be used for 245s. Hoosier has some info on this page (scroll down to "Wheel Widths").


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## Andy (Jul 16, 2003)

Andy said:


> So I guess my question is this...
> 
> Which tire would have more grip (for autocross), the 245/35/18 Hoosier A3S04s all the way around (that fits the rears properly but is .5" too wide for the fronts) or the 225/40/18 Hoosier A3S03s all the way around (that fits both front and rears properly)?


TeamZ4, I wouldn't mind hearing your honest opinion on this one. 

...and this one.



Andy said:


> What do you guys think? Should go from -2 to -1 degrees in the rear? :dunno:


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## kenkamm (May 31, 2003)

SoloII///M said:


> Incidentally, the top-finishing E46 M3 at the DC National Tour last year did quite well for himself running these tires on stock wheels. I realize it may not be the 100% optimal setup, but in lieu of purchasing four $250 Hoosiers it seems to work "OK" for local competition.


Sorry John, I must have not been clear in my conversations with you. I've been corresponding with a lot of people regarding the best AS tire setups for my E46 M3, including Andrea. Andrea and Carlos took second and third at the DC National Tour last year, but they _*were*_ running 245-35-18 A3S03s, not Ecstas. Carlos even uses the A3S03 in local competition. Most of the other guys I talk to, however, are running the Ecstas, because they are a better bargain. Some of them have also used them for track events with good results.



Andy said:


> R Compound Tires:
> Clutch in, shift to first, keep the revs right around 1,000 RPM (just above idle), let the clutch out slowly while slowly pressing the accelerator to the floor. The clutch is out, but the accelerator is now only half way to the floor. It takes about 2 to 3 seconds (total) before the accelerator is clear to the floor, any faster and the tires would have spun for sure, in fact you can feel the tires just ever so gently trying to spin while accelerating. Once the accelerator is to the floor, there is no worry about tire spin until shifting to 2nd. My 1st to 2nd shift is the same as with the street tires, but the only difference is I take .5 to 1 second to press the accelerator to the floor.


Andy, this boggles my mind. Now, my car has half inch wider wheels than yours in the back, but I don't think that would make _*that*_ huge of a difference. But my Ecstas grip like mad on launches. Much better than Michelin Pilot Sport street tires. I pretty much modulate the clutch at around 3k RPM or so, and it hooks up very quickly, at which point I mash the throttle, and I can accelerate, in first gear at full throttle, around a moderate radius turn.

One thing I have found more recently... I like more pressure in the rear than originally thought. It allows me to blast out of turns harder. I'm running around 38 psi hot in the rear now, and I like the feel of about 46 psi in the front. It's not that I need that much pressure in the front to prevent roll-over... I just like the fact that I get more feedback with the high pressures in the front. The fronts seem to provide just as much grip at 46 psi as 40 psi, they just feel better to me at higher pressures.

Cheers,
Ken


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## Andy (Jul 16, 2003)

kenkamm said:


> Andy, this boggles my mind. Now, my car has half inch wider wheels than yours in the back, but I don't think that would make _*that*_ huge of a difference. But my Ecstas grip like mad on launches. Much better than Michelin Pilot Sport street tires. I pretty much modulate the clutch at around 3k RPM or so, and it hooks up very quickly, at which point I mash the throttle, and I can accelerate, in first gear at full throttle, around a moderate radius turn.
> 
> One thing I have found more recently... I like more pressure in the rear than originally thought. It allows me to blast out of turns harder. I'm running around 38 psi hot in the rear now, and I like the feel of about 46 psi in the front. It's not that I need that much pressure in the front to prevent roll-over... I just like the fact that I get more feedback with the high pressures in the front. The fronts seem to provide just as much grip at 46 psi as 40 psi, they just feel better to me at higher pressures.
> 
> ...


Hey Ken, thanks for your response. I think I might try that higher pressure too and see how it feels. Thanks for the advise.

In regards to the tire spin I'm getting... I think half the problem is that I have too much rear negative camber. When I look at the rear tire wear, most of the wear is from the middle of the tire to the inside of the tire. I think I may bring my rear camber down to -1 degrees, that should give me better traction off the line and also help rotate the rear end around in the corners.

Keep in mind too, your car is going to hook up A LOT better then mine because you have LSD and I don't. 

EDIT : I plan on buying a set of 245/35/18 A3S04s to run at the Cendivs this year. If I can find my self another set of (cheap) wheels, I'll continue to run my Kumhos locally.


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