Michelin vs Dunlop - Staggered Setup

[BRZ_Bro]

Hey guys, first of all, I love this forum.
Second, I'm in need of some advise/help. I have 17x8 +42 in the front and 17x9 +35 in the rear. I'll be doing some Autocross and Track events, but this is also for daily driving. I am lowered on Eibach Sportlines at the moment. I'm debating on running 245/40s all around. Or I may just run 245/40 in the rear and 225/45 or 235/40 up front. My two tires of choice are Michelin Pilot Super Sports or Dunlop Direzza ZIIs. I was leaning more towards the ZIIs for the added grip, but they weigh significantly more than the PSS. So is the added weight worth it? Hopefully someone with experience could chime in. So my potential setups with each tire weight are as followed:

Michelin Pilot Super Sport

1.) 245/40 all around - 23 lbs

2.) 225/45 Front - 22 lbs; 245/40 Rear - 23 lbs

Dunlop Direzza ZII

3.) 245/40 all around - 26 lbs

4.) 225/45 Front - 24 lbs; 245/40 Rear - 26 lbs

5.) 235/40 Front - 24 lbs; 245/40 Rear - 26 lbs

6.) 235/40 all around - 24 lbs

What do you guys think?

Edit: Added a poll.

Edit 2: Added a 6th option as suggested by @raytrix; unfortunately I can't seem to edit the poll.

[raytrix]

245/40 in the rear will rub if your lowered unless you plan to run -3 camber or more while lowered. 235/40 is perfect medium for the rear with absolutely no rub at -2 camber and lowered by a lot. I have setup 17x9+35 with 235/40 Z2 all around with -2 camber all 4 corners.

[BRZ_Bro]

Originally Posted by raytrix

245/40 in the rear will rub if your lowered unless you plan to run -3 camber or more while lowered. 235/40 is perfect medium for the rear with absolutely no rub at -2 camber and lowered by a lot. I have setup 17x9+35 with 235/40 Z2 all around with -2 camber all 4 corners.

I am on Eibach Sportlines, until coils later. I'll add that info in the OP.
Are you sure? Where will they rub, because they are an exact match of stock height? And I wouldn't think they would get that close to the strut?

[DAEMANO]

@BRZ_Bro

What I've read over the past year is that for AutoX you generally want the widest+stickiest tires you can fit.

With that being said, if you get a wider than stock wheel, you're going to end up competing in a class like STX where guys run fully built cars for the class, and your partially prepared daily driver will not be time competitive (if that's your goal).

Taking the above into account, I would AutoX for fun. Get a set of Pilot Super Sports in 235/40 square or any other Max Performance Summer tire really. You'll have no fitment issues, better ride, better wet traction, less noise, better wear, and still be able to AutoX for fun not trophies than the ZIIs. If you want to be competitive, you'll have to make quite a bit more modifications to your car, which would also be fun too (just more expensive).

[BRZ_Bro]

Originally Posted by DAEMANO

@BRZ_Bro

What I've read over the past year is that for AutoX you generally want the widest+stickiest tires you can fit.

With that being said, if you get a wider than stock wheel, you're going to end up competing in a class like STX where guys run fully built cars for the class, and your partially prepared daily driver will not be time competitive (if that's your goal).

Taking the above into account, I would AutoX for fun. Get a set of Pilot Super Sports in 235/40 square or any other Max Performance Summer tire really. You'll have no fitment issues, better ride, better wet traction, less noise, better wear, and still be able to AutoX for fun not trophies than the ZIIs. If you want to be competitive, you'll have to make quite a bit more modifications to your car, which would also be fun too (just more expensive).

See that's my dilemma. I don't mind competing in STX. I've heard of a bunch of guys doing really well in STX with stock-ish FRS/BRZs. It definitely would be for fun for the most part.. but I also want to do as well as I can. That's why I asked about the weight vs grip of the PSS vs ZIIs. I know the PSS will be a better daily and weigh less, but they don't offer as much grip. I also don't mind adding mods as I'll be doing plenty of those. I just need to make this decision about tires. Michelin unfortunately doesn't make PSS in 235/40s though :/ Just 235/45.. which is too tall for me.

[raytrix]

Originally Posted by BRZ_Bro

I am on Eibach Sportlines, until coils later. I'll add that info in the OP.
Are you sure? Where will they rub, because they are an exact match of stock height? And I wouldn't think they would get that close to the strut?

This is why I exactly wrote lowered like tire tuck lowered. If you near stock height then 245/40 should be fine. It rubs the bumper tab in the rear.

[Crazy Drew]

IMO, what you need for an autocross tire and a HPDE/track day tire are two different things. Lets not even get started on daily use of the tire as this will cause unwanted heat cycles making your track tires less than desireable.

When chosing tires for either event a tire pyrometer is really needed. A lot can be learned about tire sizing, tire pressure and suspension alignment by checking your tires immediately after running on the inside of the tread, the outside and in the middle.

If a tire is too small it'll get too hot and will become greasy. If a tire is too large you won't get them up to operating temperature quick enough and lose valuable time autocrossing.

The single biggest factor in grip that'll make a difference to you is the tire compounds you choose. Only you can find out exactly what you need based off of conditions you're diving in, ambient temperature and course layout.

On a car as neutrally set up as these are from the factory with sways and weight distribution I'd go with a square tire setup initially until the pyrometer proves otherwise. If you do some reading on the tires you're interested in you can find the ideal temperature range you should operate in. A heavily staggered setup on tire sizing will honestly probably lead to understeer.

Just remember, if the tires don't get hot until the end of the run you've wasted time on track.



If the tire is the same temp inside and outside but cold in the middle, increase your pressure.

If the tire is the same temp inside and outside but hot in the middle, decrease your pressure.

If the tire is hot inside and in the middle but not outside, decrease your camber and check toe.

If the tire is hot outside and in the middle but not inside, increase your camber and check toe.

And, FWIW, you can tune you under/oversteer by changing your roll couple with wheel spacers.

[wparsons]

Originally Posted by raytrix

245/40 in the rear will rub if your lowered unless you plan to run -3 camber or more while lowered. 235/40 is perfect medium for the rear with absolutely no rub at -2 camber and lowered by a lot. I have setup 17x9+35 with 235/40 Z2 all around with -2 camber all 4 corners.

I know a couple people with 17x9 +35's running 245/40's with no rubbing, even lowered on coilovers. Not sure what camber they're running though.

[raytrix]

Originally Posted by wparsons

I know a couple people with 17x9 +35's running 245/40's with no rubbing, even lowered on coilovers. Not sure what camber they're running though.

Remember though, certain tires run wider than they are actually sized. Nitto NT05, BFG Rival, Z2 just to name a few. If they are running more of a street tire like Hankook V12, S-drives, DZ101, Michelin PSS then those are more true to size or slightly narrower than spec. Height and camber also plays a lot of factors. I already can confirm at my driving height with -2 camber that Nitto NT-05 255/40R17 tire will rub like a mother fker in the rear. I sold those tires and went with Z2 in 235/40R17 and it was perfect clearance and flush with the rim to clear the rear bumper tab. Remember I'm lower than most people that AutoX their cars so quite possibly that 235 is the clearance I need. There are those that are not as low as me with "lowered coilover" that has no issue with 245/40 Z2, those particular people are either higher than me or has more than -2 camber. It's all a math game. If you plan to run 2 finger gap or more from top of the tire to the fender then go with 245/40. No point in asking the community if your really in tune too run 245/40 Z2. Consensus will be obscured based off bias setups for strictly track/AutoX and for those people that daily drive their car with some light track/AutoX duty that can't spend money all day tweaking their height and tire selections each time when they jump between daily use and weekend warrior. My opinion is based more towards the daily/weekend warrior setup.

[wparsons]

One guy definitely has 245/40 Z2's with no rubbing, not sure what tires the others have.

The 255 NT05's have a section width of 10.1", the 245 ZII's have a section width of 9.8", over a 1/4" more space. That should be about 1/8" more room between tire and bumper tab. If that's enough will depend on the car.