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[BiscottiGelato]

After destroying the front left shoulder of a set of PSS which I only ran for a year and tracked 3 times with, I was going to settle with a set of 235/265 Direzza ZIIs on EC-7s as my new summer setup. However, while I was doing more research, it seems that it's very difficult to swap the Direzza ZIIs from side to side? From Tire Rack reviews, it also seems that the Direzza ZII albeit being better at dry grip, but the RE-11A trades only a little bit of dry performance for much better wet performance and road compliance? RE-11A also doesn't seem to have tire direction limitations....

That said, the RE-11A only comes in 245/40/18, so I'd be looking for a square setup. I am also not too sure if 245/40/18 is too big for fitment in the front (I am going with 2 degrees+ of camber with camber plate regardless tho). The diameter is also somewhat bigger than the stock 245/35 sizing (24.75" vs 25.72". Even 265/35 is only 25.3").

Any one has experience with the ZIIs vs the RE-11As? How hard would it be to fit 245/40/18 up front? How bad would 245/40/18 be given the near 4% increase in diameter? Advice much appreciated. Thanks!

[Stohlen]

You'll be fine with 245/40 up front. With stock camber I only had a minor rub on the outer fender.

I run ZIIs in 245/40 and 285/30. There is a large size difference between these two height wise but I haven't seen any issues because of it. ZIIs you do have to dismount to rotate.

[Kgolf31]

RE-11s are overrated on tire rack tests they did this summer.

Go Z11s and don't look back. you'll thank me now.

The tires will need to be dismounted and flipped to the other side and remounted if you want even wear.

[Ginger_Extract]

Originally Posted by Stohlen

You'll be fine with 245/40 up front. With stock camber I only had a minor rub on the outer fender.

I run ZIIs in 245/40 and 285/30. There is a large size difference between these two height wise but I haven't seen any issues because of it. ZIIs you do have to dismount to rotate.

What wheels are you on, APEX F8.5"/ R9.5"?

[Stohlen]

Originally Posted by Ginger_Extract

What wheels are you on, APEX F8.5"/ R9.5"?

forgestars with apex arc-8 offsets/widths.

[BiscottiGelato]

Originally Posted by Kgolf31

RE-11s are overrated on tire rack tests they did this summer.

Go Z11s and don't look back. you'll thank me now.

The tires will need to be dismounted and flipped to the other side and remounted if you want even wear.

Yeah, I actually just realized. I guess for street use the ability to rotate all 4s is more valuable. But for track use, the ability to flip inside out is probably much more useful. So I already went with the ZIIs in 235/265.

I thought about 245s up front but from most reports spacer (and camber) will be required. If I am going to go with spacers then I'd want to go more than 245. How far can one go, up front, with just camber and spacer without fender work?

[Bimmer-Bob]

Originally Posted by Kgolf31

RE-11s are overrated on tire rack tests they did this summer.

Go Z11s and don't look back. you'll thank me now.

The tires will need to be dismounted and flipped to the other side and remounted if you want even wear.

Well, you could just swap fronts and rears on the same side. Not really "even" wear, but a pretty standard way to rotate directional tires, I believe.

BTW, have you AX'ed the ZII's? About to mount a set and wondering where to start with tire pressures. The sidewalls seem super stiff! I'm thinking mid-30's might work?

[BiscottiGelato]

I am going staggered 235/265. So I can't do front back. Value of flipping inside/out is probably higher on track use where shoulder use is high and neg camber is high

[Kgolf31]

Originally Posted by BiscottiGelato

I thought about 245s up front but from most reports spacer (and camber) will be required. If I am going to go with spacers then I'd want to go more than 245. How far can one go, up front, with just camber and spacer without fender work?

I wish I could answer, but as of now my E82 is just a Daily Driver.

Until it is paid off, I'm leaving it stock. Come a couple years, it will by my SoloII Autocross car and NASA TTD Time Trials. I'll hope I can squeeze 255s up front to run a square tire...but I'm wishing alot I know.

You'll love the ZIIs

Originally Posted by Bimmer-Bob

Well, you could just swap fronts and rears on the same side. Not really "even" wear, but a pretty standard way to rotate directional tires, I believe.

BTW, have you AX'ed the ZII's? About to mount a set and wondering where to start with tire pressures. The sidewalls seem super stiff! I'm thinking mid-30's might work?

I've only driven on ZIIs briefly.

I've autocrossed on my friends E36 M which had ZIs, and you are correct that the sidewall is indeed stiff. I can't recall what he ran but they are low.

For reference, on my Hankook RS3s for autocross (which are a soft sidewall), I run 30 front and 27 rear. This is on a 3416 lb car with my in it and a 1/2 tank of gas.

Ultimately, there is no correct response, as crappy as that sounds. Pick up some sidewalk chalk and "chalk your tires". You'll see those arrows on the sidewall of the tire, and that will indicate rollover. Ideally, you want to be rolling your tire to those arrows. Take the chalk, and mark those arrows so when the tire rolls over it will wear away the chalk and you'll be able to determine where your pressures are and where to adjust.

I actually roll over a bit more on my front tires past the arrows. The arrows are not the exact pressure, more so a starting point. Going lower pressures up front and rolling past the arrows (about 1/2 way down the arrow) helps improve overall grip, so I kept them that way.

Makes sense?

Originally Posted by BiscottiGelato

I am going staggered 235/265. So I can't do front back. Value of flipping inside/out is probably higher on track use where shoulder use is high and neg camber is high

You'll need to flip for autocross as well.

I flipped my tires during the winter, and after 2 days at the track, and around 6-7 autocrosses (some with co-drivers) and my front tires are shot and at the wear bars. They are still fast, so I'm going to run them til I cord...but flipping helped my get 2 seasons out of the tires versus maybe a couple autocrosses.

It is worth the $100 to dismount and flip.

[Gary@TireRack]

The square set up will take away understeer. That's the ideal way to go for racing performance.

[Stohlen]

Originally Posted by Gill@Tirerack.com

The square set up will take away understeer. That's the ideal way to go for racing performance.

Highly disagree. That makes the car easier to drive, but not faster.

[BrokenVert]

Originally Posted by Stohlen

Highly disagree. That makes the car easier to drive, but not faster.

This again?

Part of the job of a front tire is to motivate steering. When you put more tire on the rear of the car the rear tires are less inclined to turn. This causes understeer. In a staggered setup you have to fight the inherent want of the car to drive straight, this requires more steering input and ultimately requires a bigger force to be placed on the front tires for a given turn.

More force required to turn negatively impacts cornering performance and ultimately makes your car just a tiny bit slower.

[bimmer Don]

Then I guess911 and Ferrari Have it wrong then. Because they both run big stagger set ups. F1 cars have it wrong too lol. I always like the idea of putting the biggest wheel and tire you can fit front and rear and turn your over and understeer with the suspension etc.

[Kgolf31]

Originally Posted by Stohlen

Highly disagree. That makes the car easier to drive, but not faster.

Please, I'm waiting for an explanation of this.

Originally Posted by bimmer Don

Then I guess911 and Ferrari Have it wrong then. Because they both run big stagger set ups. F1 cars have it wrong too lol. I always like the idea of putting the biggest wheel and tire you can fit front and rear and turn your over and understeer with the suspension etc.

Both car manufactures do it for looks, not performance.

F1 cars run R-Comps, which is a different topic.

You can certainly tune suspension for understeer/oversteer with camber, DA shocks, springs...etc, BUT you start with a way better set-up with square tires.

Like mentioned above, the rear tire in a staggered set-up has more grip than the front, and since this is the case, the front tires will lose grip before the rear...causing understeer.

Don't run staggered unless you're forced to, AKA me who runs in SCCA Solo and I have to conform to stock class rules.

[BiscottiGelato]

I am in the fit biggest tire possible camp.

Turning ability is limited by the front tires. You can go around a corner as fast as your front tire allows. Given the same front tire size, Square or Staggered should go around the corner just as fast. With bigger rears tho, what it allow is when you exit the corner, you have more tires to accelerate.

Just my theory tho, in no way scientific. Someone should do a controlled test of 245 squared vs 245/275 on the same car and see how the lap time plays out with a pro/consistent driver.

[Kgolf31]

Originally Posted by BiscottiGelato

I am in the fit biggest tire possible camp.

Turning ability is limited by the front tires. You can go around a corner as fast as your front tire allows. Given the same front tire size, Square or Staggered should go around the corner just as fast. With bigger rears tho, what it allow is when you exit the corner, you have more tires to accelerate.

Just my theory tho, in no way scientific. Someone should do a controlled test of 245 squared vs 245/275 on the same car and see how the lap time plays out with a pro/consistent driver.

Yes/No

Same front/rear tires will allow the car to become more neutral and allow the car to actually rotate around.

Doing this allows you to get on the gas sooner, and allow the car to track out w/out understeer worries.


You have an Open Diff...errr..."electronic LSD". I'd worry about the most grip as possible before accelerating out of a corner. Just IMO.

YMMV.

If you could fit 255s up front, squared would be the best option. 245s would be a give and take.

[Jazzy]

Wow, wide range of topics on this thread. As someone who has taken up autocrossing for the last 2-3 years, here some of my thoughts, opinions.

Tire pressure for autox: Low to mid 30's is normal tire pressure for street driving. For autox I would say a minimum of 38lbs up front or you will easily damage outside shoulder. (learned this the hard way with re-11's and now running ZII and wear is right at the indicator).

RE-11(not RE-11A) vs ZII: ZII superior in both wet and dry. However for street driving I might choose the RE-11A, as it would be much closer in traction and the first thing I noticed about the ZII is large amount of tire noise.

Staggered or not: Not an expert by far, but I would prefer the idea of most tire possible. I would think a very experienced driver could rotate the car with throttle and braking (I'm not there yet but working on it). Question: If you took a Ferrari, Porsche, or whatever and reduced its rear tires to match the front, would that make it faster? Probably not. Also, I would say that a square or neutral setup would also be more difficult to drive, as now you need to control oversteer more than understeer.

[blutattoo]

You could run 255/35/18 R-S3's square. I run 255's up front w/2 deg neg camber on apex arc-8s without rubbing. Just a thought if you want the biggest contact patch. I ran the RE-11's prior to that and they were great at first. Really fell off after 8-10 track days, but they lasted longer than I expected so I'm guessing the RE-11a's are even better.

For most BMWs square is better. Just look at the 135's running in WCTCC they all run that same setup. All BMW's running grand-am and alms run square setups. It's not cut and dry, but generally front engine rear drive benefits from the square setup. Rear engine or mid engine the weight transfers differently. Those cars rotate a bit easier so the push that comes from the staggered setup is negated by the chassis's ability to rotate.

[Stohlen]

Originally Posted by Kgolf31

Both car manufactures do it for looks, not performance.

Both manufacturers do it for traction, not looks... Thats the whole point. Turn the car with the throttle.

[BiscottiGelato]

I think the argument is to reduce rear tires to induce essentially some oversteer to improve turning. Sacrificing corner exit grip.

No idea whose right. I say a real life controlled experiment might be the only way to settle this. From 235 square and staggered to 255 square and staggered. Same car, same rims, same tires, same driver, same conditions and post some lap times. That'll be the only way to settle this.

[Stohlen]

Originally Posted by BiscottiGelato

I think the argument is to reduce rear tires to induce essentially some oversteer to improve turning. Sacrificing corner exit grip.

No idea whose right. I say a real life controlled experiment might be the only way to settle this. From 235 square and staggered to 255 square and staggered. Same car, same rims, same tires, same driver, same conditions and post some lap times. That'll be the only way to settle this.

Even then that wouldn't be a good test, as rims that are ideal for 235s aren't ideal for 255s and the 255s will perform worse than they would on a properly sized wheel. Minor yes, but for really scientific test, you'd need to account for that.

[Kgolf31]

Originally Posted by Stohlen

Both manufacturers do it for traction, not looks... Thats the whole point. Turn the car with the throttle.

Easier said than done.

Rear Engine, RWD vs Front Engine RWD.

Lets not forget that you don't have an LSD, so good luck trying to rotate the rear with the 1 wheel drive.

Originally Posted by blutattoo

You could run 255/35/18 R-S3's square. I run 255's up front w/2 deg neg camber on apex arc-8s without rubbing. Just a thought if you want the biggest contact patch. I ran the RE-11's prior to that and they were great at first. Really fell off after 8-10 track days, but they lasted longer than I expected so I'm guessing the RE-11a's are even better.

Good information. Glad you can run 255s w/out rolling the lip