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Old 11-08-2012, 04:53 PM   #1
MrPedals
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Join Date: Nov 2010
Location: Santa Cruz, CA
Posts: 56
My Ride: E46 M3, Mystic Blau
E46 M3 - The truthiness about square setups and daily driving [TLDR]

In my quest to reduce annual costs, and increase performance about 1 year ago I decided to dump my staggered wheels and go with some very nice Apex Arc-8's in a square 18x9.5 et35 setup with some spacers in the back to make it fit. Here is my observations for anyone thinking of doing something similar.
For reference, I commute about 90miles to work and attend approx. 2-4 HPDE's a year.

Object 1: Decrease overall costs

Due to staggered fit, and several track days, my precious Michelin PS2's died in a lot less time than I had previously budgeted. I decided that the best solution for this was to be able to rotate my tires to make them last longer, as well as utilize michelin's 30,000 mile tire warranty.
"30,000 Mile Manufacturer's Treadwear Limited Warranty
Pilot® Super Sport tires carry a 30,000 mile limited warranty in addition to the standard materials and workmanship warranty for treadwear or mileage.
Available on:
Pilot® Super Sport
Speed Rating: [(Y), Y]* Mileage Warranty Exceptions
Split fitments - If your vehicle has tires of different sizes on the front versus the rear axles, your tires cannot be rotated as recommended. Therefore, the mileage warranty on each rear tire will cover half the number of miles as the standard mileage warranty for that particular tire line.
ZP (Zero Pressure) tires - The maximum mileage warranty for ZP tires is 30,000 miles."


Object 2: Increase "Performance" of the car

I put the word performance in quotes because it is subjective. The e46 M3 performance in it's natural OEM state is quite high already. Improving on it's street performace, to me at least, meant increasing cornering agility, stopping ability, acceleration and doing it with a reasonable budget. To be more specific, the car with staggered tires and OEM wheels understeers quite easily (IMHO) and the acceleration is fun, but nothing to really write home about.

*EDIT* Adding pictures to help make the post less bland

Old Staggered setup on Forgestar F14's
Photobucket

So how did it do?
After I put the new wheels and tires on (Michelin PSS 265/35/18) I noticed the following characteristics change.

I immeadiately noticed that the car was much less directionaly stable, in that, it always wanted to turn instead of going in a straight line. This is great for race cars but very aggravating when commuting to work. When commuting to work, I drive a mixture of fast 50 mph+ sweeping turns for 20 miles then to a straight boring freeway for an additional 20 miles. In theory it should have been fun for half the trip and a pain for the second half. Instead it was just confusing and frustrating the entire time. What was the problem? Why did the car want to dart randomly? Why did the steering get so numb? On center feel was attrocious...what happened?
The fatter gripper rubber exposed some things that were wrong with the rest of the car, here they are in the order that I discovered them:

1. E46 M3 Differentials use a device that "automatically" senses which wheel to apply grip to and then sends power to that wheel with a clever LSD. The only problem is, after talking to several people who build custom LSD's for racecars, the stock LSD gets a little overwhelmed by so much rubber. It still works, it just doesn't work as good, and it starts lock up the diff at the wrong time, namely, before entering the corner. This causes the car to want to randomly understeer when lightly turning into a fast corner. Very annoying. The sensation is very subtle and 90% of people won't feel it or realize what is going on, they will just drive the car and might tell you it felt a little weird.

New setup with Apex ARC-8's
M3, Uploaded with Snapbucket (Original)

2. While my stock suspension did actually fit the wheels and tires with no problem, I discovered that I needed an alignment. One thing leads to another and soon enough, to get the "proper" alignment on the car, I bought Vorshlag camber plates, and Turner rear camber arms. From what I've heard, most people doing a square setup will also replace the stock suspension with aftermarket and this is a necessary step. I bought this stuff simply planning for when I replace my stock shocks and springs. The new alignment helped a lot, but there were still more problems.

3. Tire pressures on a stock setup WILL NOT WORK for a square 265/35 setup. Period. Every where you go to get the car worked on they will hand you the key and say, "...And we set the tire pressure to OEM specs" and you just shake your head. I found that, at a minimum, I had to run 36 PSI all around for the car to feel somewhat normal. I am now running about 38psi for street driving. The sidewalls of a 265/35/18 tire are just too tall and subsequently too soft to feel the same as a 225/45/18 at the same pressure. The amount of steering feel lost because of this was amazing, directional stability at high speed changed drastically between the OEM and 38psi pressures.

4. OEM shocks, sway bars, and springs are like jello at high speeds, and feel downright scary at the track. The new rubber really put a lot of extra pressure on the whole system and to quote my friend (who is a BMW mechanic and races an E36) "The tires and brakes are AWESOME, and there's plenty of power, but...the suspension is crap."

5. The aftermarket FCABs I had on the car were @ about 30,000 miles when I put the new rubber on, and they just simply couldn't handle the task. I had Rogue engineering FCABs in the "street" compound and with OEM tire sizes or even 235/40/18 rubber, they felt fantastic. But with 265/35/18 they were simply overwhelmed. After a recent track day one of them eventually failed and the right front wheel started to move a little bit for and aft while driving, causing the car to drive really crazy again. So lesson learned about 265 rubber vs. FCABs? Tack compound.

So really, by addding on the extra rubber, it led me down a very slippery slope of fixing one thing after another. Am I unhappy? No. Do I wish that someone had explained this to me very bluntly beforehand? Yes.

*Discuss*

Last edited by MrPedals; 11-08-2012 at 09:00 PM.
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Old 11-08-2012, 08:42 PM   #2
MrPedals
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If I could do it again...

If I could back in time I would have done it slightly different...I think.

I ended up spending waay more money on the car after the square setup just to make it daily drive as good as the previous setup. What could I have done to mitigate this?

1. Just leave the car relatively stock...this would have been far, far cheaper. But the car is way more exciting to drive now, so I don't think I would have settled for this.

2. Gone with a square setup, but smaller. I think now that in the end, a daily driver with street FCABs and RTABs, and stock suspension shouldn't really run rubber wider than 255 in the front, and in reality, probably 245 is the upper limit for keeping the nice crisp steering feel. I think that switching to fresh Track compound RE FCABs has made the biggest difference in driving experience. I can FINALLY feel what the wheels are doing again. I think 18x9 wheels might have been a better call for a car that won't be seeing as much track time.

3. Bought a different car to track. I did this in fact, bought a track ready E30, and it has been far, far more fun on the track than the M3. You're just not racing at these HPDE's and if you don't care about winning then it's more about how the car feels. Having something cheap that you can punish at the track is worth way more money than all the pain and suffering of trying to make your street car work right in both environments. All these mods to the M3 and it is still rubbish at the track compared to a decently setup track 330i.

New track car
"little" car

4. 3.91 differential. I actually did install a 3.91 diff I bought off craigslist, and while it was amazing, it had problems of it's own. I still want to get it fixed and put back in the car...I can tell you this, out of all the sh!t I've put on this car, a 3.91 was by far, by a huge margin, the best mod I did. It just really makes the car feel like the way it should have come from the factory. Nothing else makes your eyes open up with excitement as the diff.

Last edited by MrPedals; 11-08-2012 at 09:03 PM.
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Old 11-11-2012, 06:14 PM   #3
Ballistic325
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Nice write up and good for M and non-M owners....

Agreed that a 9.5" width square setup is just too wide. 8.5-9" width would be plenty but might not look like they fill the guards

Good points on the sidewall heights as well. You'll notice a huge difference in handling with taller rubber compared to shorter or standard.

Do you rotate your wheels regularly now?
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Old 11-12-2012, 09:15 AM   #4
MrPedals
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Quote:
Originally Posted by Ballistic325 View Post
Nice write up and good for M and non-M owners....

Agreed that a 9.5" width square setup is just too wide. 8.5-9" width would be plenty but might not look like they fill the guards

Good points on the sidewall heights as well. You'll notice a huge difference in handling with taller rubber compared to shorter or standard.

Do you rotate your wheels regularly now?
Yes, I rotate them often now. The tires are lasting longer, I don't know if I'll get 30,000 miles out of them, but I think I will get more than 15,000 which is all I got last time.
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Old 06-04-2013, 11:33 AM   #5
MrPedals
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FYI. Got the tires rotated again yesterday, they are currently at 5/32's and the mileage is 96,405 so about 26,000 miles on them including a track day pulling double duty (two separate drivers in two different groups). Finally replaced the rogue street RTABs with Blue track compound and this was the final piece to the puzzle. The car finally drives the way I want it, and it only took about 6 thousand dollars of changes to mitigate.
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Old 06-04-2013, 12:39 PM   #6
Grande D
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Nice write up. After driving and purchasing square and staggered setups, I agree with most of your comments. The downsides are largely the result of the rubber being so wide all around as you said. A square setup in itself does not reduce directional stability and such. Impacts are also harsher with wider front tires. Also, a 265/35/18 actually is a shorter tire than a 225/45/18, but the extra tire width certainly would reduce steering feel.
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Old 06-04-2013, 05:50 PM   #7
MrPedals
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Quote:
Originally Posted by Grande D View Post
Nice write up. After driving and purchasing square and staggered setups, I agree with most of your comments. The downsides are largely the result of the rubber being so wide all around as you said. A square setup in itself does not reduce directional stability and such. Impacts are also harsher with wider front tires. Also, a 265/35/18 actually is a shorter tire than a 225/45/18, but the extra tire width certainly would reduce steering feel.
Probably true about that 265/35 vs. 225/45. I was actually running a 235/40 front before the switch to square and the difference was enough that I stopped scraping my bumper in certain scenario's (speedbumps at work, etc.) because it was higher with the 265/35.
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