F80 ZCP: Wider Tire Size Fitment

[mose121]

I have a 2016 F80 ZCP and am looking to go with wider tires on the stock wheels on both the front and rear. I do track the car occasionally in advanced groups and I'm getting pretty tired of going through front tires in a half day track day. I have lots of track experience with Pilot Super Sports on other cars and have never had this problem. The stretched sidewalls on the F80 ZCP 20" front tires is just completely inadequate for heavy loads. The tires just roll over too much unless you jack up the PSI which is counterproductive at the track. It's a constant battle between a low enough pressure to maximize grip and fight the PSI increases as the session goes on vs. a high enough pressure not to rapidly tear up the sidewall under load. I do load the car up with luggage and passengers quite often and do not want to have any rubbing at all. Car is also my daily driver and will not be lowered in the future. Looking to go with MICH PS4's. Any insight you may have would be greatly appreciated. Saw a mention in another thread about wider tire discussions so I tried searching but came up empty.

[wigaster]

You are overdriving the tires and no matter how you compromise your tire pressure, tire width, etc etc you are still driving a compromised tire (PSS) on a fairly heavy car. Wider is not going to fix your problem nor is going with the PS4S. Solution for your problem is dedicated track wheel and tires (with proper rubber). This may be not what you were hoping to hear but everyone is going to tell you the same thing. Good luck!

[mose121]

Originally Posted by wigaster

You are overdriving the tires and no matter how you compromise your tire pressure, tire width, etc etc you are still driving a compromised tire (PSS) on a fairly heavy car. Wider is not going to fix your problem nor is going with the PS4S. Solution for your problem is dedicated track wheel and tires (with proper rubber). This may be not what you were hoping to hear but everyone is going to tell you the same thing. Good luck!

Well aware of all that but this isn't my dedicated track car and only sees the track occasionally. A dedicated wheel/tire set for the track just doesn't make sense for me on this car. It's only going to see the track 2-3 times a year vs our dedicated 997.2 that we run 10-15 times a year. The tires clearly have more grip to offer, but the sidewall can't support it. I've run PSS's on several cars and never had this issue before. I'm certainly pushing the car fairly hard but barely to the point where the tires even make a chirp let alone a squeal, and nowhere near a screech/limit of adhesion. I'm going to install camber plates soon to help with some of the outer edge wear at the track and improve turn in, however the sidewall is still too stretched in the stock size for track use. No matter what it's always going to roll over on the sidewall under heavier load unless the pressures are jacked up. A wider tire without any stretch should theoretically offer better support and less deformation to reduce the rollover tendency to some extent. In combination with the camber plates it should help reduce the excessive edge/sidewall wear to an acceptable level.

[mose121]

In desperate need of new tires and need to make a decision asap. I can't believe no one has run into this same issue.

[spyderbret]

Just found your thread. I have the same issue. M3 with comp package and I tore up the front tires very quickly. I had Michelin Pilot Super Sports but couldn't find replacements in my size. I have the carbon cermaics with the 20" 666's so options are fairly limited. I went with the PS4S' in stock sizes. I am having camber plates installed in the next week or two before I get it on the track again.
I only put about 60 miles on the tires since install and have been restrained while I wear them in a bit. Initial feel is really good but there seems to be a little more sidewall flex than the PSS'. I'm not convinced it's in a bad way though because once it set it feels very precise and predictable. I think camber plates and a good alignment will do wonders for this car.
This is my DD and I have a Cayman R that I track often. So almost same situation. I wish I had more time on the tires to give better feedback but here we are.

[dongerkim]

Hello, Sorry to bump this thread from the dead but I am also in the exact same situation. Ive just blown through front tires... I would normally be ok with having a dedicated track set but it’s just not very feasible with my situation here (I am on European delivery for 3 months and at the Nurburgring often). At this point, I am also ready to change to 18” 513M’s but can’t seem to find the german F8x classifieds.

How has the PS4S worked out? I am considering that as one option, as well has misfitting cup2 tires. It really seems like we have many really bad options for tires for 20” 666 at the moment. Any input would be greatly appreciated!

[spyderbret]

I added the Ground Control camber plates and they helped a lot with tire wear. We went a little conservative with the camber settings (2.5 or 2.6) but there is more to be had if you want it. My car will only see a few track days a year so this is good enough for me. I do feel like the tires got a little louder after the last track session but I wont be able to confirm until I replace them. Wear has been great so I think I will get another 8-10k miles before they need replacing. They currently have about 10k on them now.

The grip levels in spirited driving have been great too. Love the tire, love the performance, not so sure about the noise as it's more pronounced on some surfaces versus others. They are definitely worth trying out!

[dongerkim]

Originally Posted by spyderbret

I added the Ground Control camber plates and they helped a lot with tire wear. We went a little conservative with the camber settings (2.5 or 2.6) but there is more to be had if you want it. My car will only see a few track days a year so this is good enough for me. I do feel like the tires got a little louder after the last track session but I wont be able to confirm until I replace them. Wear has been great so I think I will get another 8-10k miles before they need replacing. They currently have about 10k on them now.

The grip levels in spirited driving have been great too. Love the tire, love the performance, not so sure about the noise as it's more pronounced on some surfaces versus others. They are definitely worth trying out!

Thanks for the reply. I don’t know how readily available camber plates are available here in germany and really at a cross roads for all mediocre choices as i leave in 6 weeks. I did a full day on new PS4s and thought i had less sidewall flex than the PSS. i’ve been monitoring the sidewalks very closely, changing my driving style a bit on hard breaking and then ins (and really taking it easy on a couple of corners that just seems to always understeers no matter what i do).

I’ve also bumped the pressure up from 35 psi all around to 38psi all around which i think helps with the wear, just not as greg grip level wise. I also considered getting a cheaper 18” wheel set while i’m here but arranging shipping back seems like a pita. I’ll look into camber plates and may be my best option at this point, but i’ll likely have to take them off in 6 weeks for export which is another cost.

[spr]

I'm in the same boat. I added the BMW HAS kit and lowered to GTS spec street at 14" around which gave me -1.8 front negative and dialed out the rear camber to -1.6 which gives better traction, balance and more bite front. I'm surprised BMW is running a 265 on a 9. It's stretched. A 255/30 would handle better on a 9 and have way better steering feel. I ran this on my e92 before upgrading rims and going 275/305. Another idea is go Nitrogen and higher pressure cold. It will get to your target and have less expansion which is exactly what you want. Save that it's new rims and tires, e.g. 9.5 or a 10 front with wider to combat the issue.

Are you running 2.5 all the time on the street as a DD? That will eat the insides quickly. I found -2 was fine but more than that will eat.

I'd say perhaps get a set of rear 666m and run 275 or 285. However, for that cost you can easily get a new set and do better.

[dongerkim]

Originally Posted by spr

Are you running 2.5 all the time on the street as a DD? That will eat the insides quickly. I found -2 was fine but more than that will eat.

I'd say perhaps get a set of rear 666m and run 275 or 285. However, for that cost you can easily get a new set and do better.

Do you mean 2.5 bar? or 2.5 degree negative camber? I am running 2.7 bar which pans out to be about 38psi up front. It certainly doesn’t feel as good as handling wise.

2.5 degree negative camber? I wish, I’m not sure if camber plates would be worth the money for the few weeks i’m here :/. The problem is, i think i know most of the solutions but all have some compromise and most don’t seem to make sense while i’m on vacation lol

[mose121]

FYI I ended up buying the PS4S in the OEM 265/30/20 size. It looks 100 times better and has zero stretch on the sidewall compared to the stock BMW Star Spec PSS. I would assume the PS4S is similar to the non BMW star spec PSS's that have a wider tread width than the BMW star spec version, which is at least a half an inch difference in tread width. That half inch makes a BIG difference. I should note that my car is not lowered so can't comment on anything related to rubbing concerns aside from that my car does not rub even when heavily loaded in a hard turn.