[ZM2]

Originally Posted by E90convert

Thanks for your insight! I did enjoy the stagger feel for the 255/275 PS4S I ran over the summer, the car felt balanced overall. I had a good rear grip, except when the tires started overheating (stock power). The rears would lose grip more toward the end of a session; this problem will probably go away with a better compound. So, at this point, I do not feel the need to increase the width of the rear tire. The car would certainly default to understeer quickly as the 255 section overheated. A better compound and slightly wider may benefit.

Would the 30mm stagger be too much and result in a lot of understeering at the limit?

Just remember that understeer happens b/c of overdriving the fronts, not b/c of stagger differences. That said, there is certainly a difference in balance and feel every 10mm stagger you add or remove.

I'd say it depends on your driving style--if you're still working on not over driving the fronts and are a bit shy with the throttle, stay with 20mm stagger.

If you're good at managing and driving to and not over front grip limits, and like to be more aggressive with the throttle and a tiny bit of oversteer/rotation doesn't bother you, try 30mm stagger--it will be slightly faster.

I once ran 265/305 R7's, and that setup has so much grip, especially coming off the corners! But, it was a bear to drive. You had to be so diligent with your driving to not overwork the fronts b/c of how much it shifted the balance of the car. Never again!

What you really want is four wheel drift coming in and out the corners. That is best managed with a 20mm stagger and why I run 18x10 & 18x10.5 275/295. Best setup I've ran on the car, yet, and you'll get a similar F/R balance feel with 255/275.

[Track/S]

Originally Posted by ZM2

Just remember that understeer happens b/c of overdriving the fronts, not b/c of stagger differences. That said, there is certainly a difference in balance and feel every 10mm stagger you add or remove.

I'd say it depends on your driving style--if you're still working on not over driving the fronts and are a bit shy with the throttle, stay with 20mm stagger.

If you're good at managing and driving to and not over front grip limits, and like to be more aggressive with the throttle and a tiny bit of oversteer/rotation doesn't bother you, try 30mm stagger--it will be slightly faster.

I once ran 265/305 R7's, and that setup has so much grip, especially coming off the corners! But, it was a bear to drive. You had to be so diligent with your driving to not overwork the fronts b/c of how much it shifted the balance of the car. Never again!

What you really want is four wheel drift coming in and out the corners. That is best managed with a 20mm stagger and why I run 18x10 & 18x10.5 275/295. Best setup I've ran on the car, yet, and you'll get a similar F/R balance feel with 255/275.

Have you tried 295 square?

[ZM2]

Originally Posted by Track/S

Have you tried 295 square?

I haven't. That'd require some modifications I'm not willing to do since my car is primarily a daily driver. 275/295 bolts on without issue.

If you have the suspension upgrades and setup to make the car neutral on 295 square it'd be quicker than 275/295.

Would be interesting to do back-to-back tests to know by how much and how the balance feels b/n the two setups.

[Track/S]

Originally Posted by ZM2

I haven't. That'd require some modifications I'm not willing to do since my car is primarily a daily driver. 275/295 bolts on without issue.

If you have the suspension upgrades and setup to make the car neutral on 295 square it'd be quicker than 275/295.

Would be interesting to do back-to-back tests to know by how much and how the balance feels b/n the two setups.

I've been in 285 square for a little over a year, I don't want or plan to go back, now I'm in neova ad09 285/30/18 square, it's wider than the 285/35 I used before, the driving is from another planet.

There is no other configuration that works better than this one on the f87.



Ad09 285/30 on 10.5:

[ZM2]

Originally Posted by Track/S

I've been in 285 square for a little over a year, I don't want or plan to go back, now I'm in neova ad09 285/30/18 square, it's wider than the 285/35 I used before, the driving is from another planet.

There is no other configuration that works better than this one on the f87.



Ad09 285/30 on 10.5:

I mean, the 71RS and CR-S v2 are definitely quicker tires than the AD09, but maybe this is your street setup. Looks pretty sweet!

My roads are a little too crappy for 30-series, so stuck with 275/295/35 for the street, as well.

[medphysdave]

Admittedly I'm smitten with the 295 square setup. I wanted to prefer the stock staggered setup on the street because BMW designed it that way and I'm an enthusiast, but the 295 setup feels safer and much more confidence inspiring in DD and track. The added front grip suits my ogerish style of driving.

[Track/S]

Originally Posted by ZM2

I mean, the 71RS and CR-S v2 are definitely quicker tires than the AD09, but maybe this is your street setup. Looks pretty sweet!

My roads are a little too crappy for 30-series, so stuck with 275/295/35 for the street, as well.

I am looking for a tire that is not noisy, durable and excellent on wet roads, on the track it is a second slower than A052, for me it is enough.

The cost of 285/30 size is 160$, therefore they have no rival.

[mike082802]

Originally Posted by Track/S

I am looking for a tire that is not noisy, durable and excellent on wet roads, on the track it is a second slower than A052, for me it is enough.

The cost of 285/30 size is 160$, therefore they have no rival.

Wow here in the US they're almost $400 a tire.

[///MPhatic]

Originally Posted by medphysdave

Admittedly I'm smitten with the 295 square setup. I wanted to prefer the stock staggered setup on the street because BMW designed it that way and I'm an enthusiast, but the 295 setup feels safer and much more confidence inspiring in DD and track. The added front grip suits my ogerish style of driving.

295 square is such a difficulty. It's better left to track/beat-up cars IMO.

BMW didn't design any variant of the road F87 to be a true track car. The road cars are supposed to be playful and fun.

[E90convert]

The ~$5k to get to a forged wheel 275 square setup + larger sway bar might not be worth it right now. Perhaps money is better spent keeping my existing 19x9.5/10.5 and spending $1500 on 255/275 35/19 RE-71RS setup and work on not overdriving the fronts.

[ZM2]

Originally Posted by E90convert

The ~$5k to get to a forged wheel 275 square setup + larger sway bar might not be worth it right now. Perhaps money is better spent keeping my existing 19x9.5/10.5 and spending $1500 on 255/275 35/19 RE-71RS setup and work on not overdriving the fronts.

More grip until you're ready for it just hides mistakes. An instructor buddy of ours here ran 255/285 for years and he's so smooth he'd maximize those tires every time out and run impressive times.

And, even tho I just spent two days at Portimao (right before Verstappen was there, hah!) testing the new M4 GT4 with the Euro GT4 champ and managed to get within 1.8s of his best time on a 2-minute track that I've never been to and in a car I've never driven, I'm guilty of leaning on more grip and aero to cover up mistakes. His skills allowing him to drive that car like a mix b/n a Miata and an indoor kart to maximize available grip is what let him snag a tenth of a second in each corner to pull away from me over the lap (that's all it takes, 0.1s each corner to smoke your competition and old self!). It was amazing to behold, but it is his day job!

Separately, the unboosted brakes in the M4 GT4 are gnarly! You have to hit the pedal with 120-bar of force if you want maximum decel. Even all my cycling was worn out after two days. Loved that car tho, so balanced--even got to where I was perfectly comfortable driving it with TC off!

[Track/S]

Originally Posted by mike082802

Wow here in the US they're almost $400 a tire.

I have bought 4 more in case they are going to raise the price

Originally Posted by ///MPhatic

295 square is such a difficulty. It's better left to track/beat-up cars IMO.

BMW didn't design any variant of the road F87 to be a true track car. The road cars are supposed to be playful and fun.

2 years ago when we went on mountain road with 400hp EVO's I had to sweat to be able to follow them, now on square setup I have to wait for them because they get lost back there.

They do not come close either braking or turning or coming exit of corners.

[dvas]

Originally Posted by E90convert

The ~$5k to get to a forged wheel 275 square setup + larger sway bar might not be worth it right now. Perhaps money is better spent keeping my existing 19x9.5/10.5 and spending $1500 on 255/275 35/19 RE-71RS setup and work on not overdriving the fronts.

I think bang for buck, just getting a set of 10 inch Apex wheels and running 275 square RE71RS, NT01s or similar will wear better and be faster overall than forged wheels and a square setup. Unless you're competing for tenths, I don't think truly forged wheels are worth the $, and I'm not sure why you think a sway bar is needed. A better investment would be adjustable coilovers like the Ohlins R&T or Bilstein PSS10

[ThreeStripes]

I thought I needed a larger sway only to swap suspension setups and realized what I needed was higher spring rates and better damping via OG spec Nitron R1s.

[E90convert]

Originally Posted by dvas

I think bang for buck, just getting a set of 10 inch Apex wheels and running 275 square RE71RS, NT01s or similar will wear better and be faster overall than forged wheels and a square setup. Unless you're competing for tenths, I don't think truly forged wheels are worth the $, and I'm not sure why you think a sway bar is needed. A better investment would be adjustable coilovers like the Ohlins R&T or Bilstein PSS10

Getting Apex EC-7 18x10 ET33 would save about $1300 from that package, but that is still $3700 vs $1500 for just tires on my existing wheels. Aside from the unsprung mass, the forged wheels are stronger, and I would be more resistant to cracks when hitting curbs.

I am considering a larger sway bar because I significantly increase front-end grip (1in wider wheel, 35mm wider tire). A larger front bar would decrease body roll due to the increased grip.

How would you compare 255/275 + coilovers against a 275 square forged + large front bar?

[ZM2]

Originally Posted by dvas

I think bang for buck, just getting a set of 10 inch Apex wheels and running 275 square RE71RS, NT01s or similar will wear better and be faster overall than forged wheels and a square setup. Unless you're competing for tenths, I don't think truly forged wheels are worth the $, and I'm not sure why you think a sway bar is needed. A better investment would be adjustable coilovers like the Ohlins R&T or Bilstein PSS10

Agreed with this and ThreeStripes.

I have PSS10 and run them 3/10 on the street, 5-7/10 depending on the track, no front sway bar and I have no desire to add one. The PSS10s keep the car flat enough without changing sway bars while still allowing to drive over curbs, and are excellent on track.

Being able to adjust them on a lowered car with big rubber without needing to take the wheels off is a bonus.

[AmuroRay]

Originally Posted by E90convert

Getting Apex EC-7 18x10 ET33 would save about $1300 from that package, but that is still $3700 vs $1500 for just tires on my existing wheels. Aside from the unsprung mass, the forged wheels are stronger, and I would be more resistant to cracks when hitting curbs.

I am considering a larger sway bar because I significantly increase front-end grip (1in wider wheel, 35mm wider tire). A larger front bar would decrease body roll due to the increased grip.

How would you compare 255/275 + coilovers against a 275 square forged + large front bar?

I have a linear spring conversion kit for my PSS (non adjustable) just waiting for the camber plates.

If you're running coil overs, you'll want to up the spring rate before you start adding swaybars, and if you have adjustable shocks, the range they work is wider than something like my PSS system.

With both (and I've only run my car with the M235i stock stagger) You can expect a square setup to be more neutral.

[monstruo]

Planning to make custom wheels and would like to minimise on the use of spacers. Folks running on 295/30/R18 square can chip in on the F/R wheel width/ET/Spacers?

Just curious as well, did anyone manage to fit 295/35 R18 on their front?

[RugbyBro]

Food for thought here - I've seen some insanely fast TA times run on 275/40R18 square setup on a F80 with super 200s (CR-S). Not sure if that side profile will work in front on F87 but worth a try if it does.

[E90convert]

Originally Posted by RugbyBro

Food for thought here - I've seen some insanely fast TA times run on 275/40R18 square setup on a F80 with super 200s (CR-S). Not sure if that side profile will work in front on F87 but worth a try if it does.

Interesting to note! Somethings get better, some get worst, with a 40 vs 35. Maybe the higher load rating allowed the tire pressures to go lower without ruining response or rolling the side wall and result in better grip.

[RugbyBro]

Originally Posted by E90convert

Interesting to note! Somethings get better, some get worst, with a 40 vs 35. Maybe the higher load rating allowed the tire pressures to go lower without ruining response or rolling the side wall and result in better grip.

Yup - loss in acceleration but gain in speed carried thru corners. I think seeing it first hand also made me realize that you can run reasonable sizes and still be extremely fast.

[ZM2]

Good article at GRM about RE-71RS & RT660 performance as they wear: https://grassrootsmotorsports.com/ar...d-longer-life/