What Size PSS for OEM 19" Wheels?

Padfan9 · 06-06-2015, 11:33 AM

Quote:

Originally Posted by gthal

Quote:

Originally Posted by Padfan9

Yea that's what I was thinking! Do you think the 40Mm difference will hurt performance at all? I'm confused as to why the other guy said that?

Here is my take. The 40mm wider rear is 20mm wider stagger than OEM. This, in theory, keeps the rear more planted and allows the rear to go into a corner faster with more stability. This, in theory, would allow you to push a smaller front tire beyond its limit easier and cause understeer. IMO only, this is not something you would notice unless you were at the very limit on a track. Certainly not on the street. The rear will rotate less with a wider rear and more grip. That simply puts more stress on the front but, IMO, this car doesn't understeer much anyway so I don't personally think it will be an issue.

I'd love others (CanAutM3) view on this but that would be my view.

Thank you so much for your help. Last question for you! Do I you think the 305 will be flush with an 11 inch width? I don't want the tire to bubble.

gthal · 06-06-2015, 11:36 AM

Quote:

Originally Posted by Padfan9

Thank you so much for your help. Last question for you! Do I you think the 305 will be flush with an 11 inch width? I don't want the tire to bubble.

Yes... they will fit an 11" wheel well.

JoeFromPA · 06-07-2015, 04:50 AM

I'd like to hear more about hydroplaning on Michelin PSS or a similar street tire.

I'm considering going from stock PSS on 18" wheels to either 19" wheels and wider tires or staying on the 18" but going with a 275/295 front/rear in Michelin PSS.

However, I've needed this car to bring me safely through some really hairy stuff in the rain. I don't want to significantly deteriorate that capability.

Mark's M · 06-07-2015, 04:23 PM

Quote:

Originally Posted by gthal

Here is my take. The 40mm wider rear is 20mm wider stagger than OEM. This, in theory, keeps the rear more planted and allows the rear to go into a corner faster with more stability. This, in theory, would allow you to push a smaller front tire beyond its limit easier and cause understeer. IMO only, this is not something you would notice unless you were at the very limit on a track. Certainly not on the street. The rear will rotate less with a wider rear and more grip. That simply puts more stress on the front but, IMO, this car doesn't understeer much anyway so I don't personally think it will be an issue.

I'd love other (CanAutM3

) views on this but that would be my view.

I agree with gthal which is why I qualified my comments with "extreme driving". On the street, the increased stagger won't make any noticeable difference.....provided you heed gthal's advice re pushing it way, waaay, waaaay too hard.

Jadski · 06-22-2015, 04:10 PM

Thank you for all the info on your tire size thread. I recently finished a track weekend at Barber Motorsports and running a completely stock set up. My front tires and pads are toast. I'm still a novice driver but run blue group with an instructor with Chin Motorsports and ran mixed solo and instructed group 2 with PCA. My instructors have had me driving in partial MDM.

My m4 is my daily driver. I have the 19 inch rims. I'm going back with stock pads for now because I'm not convinced about the carbotech's or pagid rs29's, especially since I only do 3-4 events/year. My question is the tires. I definitely encountered a lot of push during hard cornering and felt like it scrubbed off a lot of my speed. It was also a very hot day and MDM made it hard to accelerate out of corners. My instructor and I definitely felt like tires were an issue. In your thread, you recommended going with the 275/35-295/35 combo; but then later I saw in another thread that CanAutM3 is now running a square setup with 275's.

My instructor recommended running a square setup if I can, so I can rotate tires.

Any updates or opinions?

CanAutM3 · 06-22-2015, 04:33 PM

Quote:

Originally Posted by Jadski

Thank you for all the info on your tire size thread. I recently finished a track weekend at Barber Motorsports and running a completely stock set up. My front tires and pads are toast. I'm still a novice driver but run blue group with an instructor with Chin Motorsports and ran mixed solo and instructed group 2 with PCA. My instructors have had me driving in partial MDM.

My m4 is my daily driver. I have the 19 inch rims. I'm going back with stock pads for now because I'm not convinced about the carbotech's or pagid rs29's, especially since I only do 3-4 events/year. My question is the tires. I definitely encountered a lot of push during hard cornering and felt like it scrubbed off a lot of my speed. It was also a very hot day and MDM made it hard to accelerate out of corners. My instructor and I definitely felt like tires were an issue. In your thread, you recommended going with the 275/35-295/35 combo; but then later I saw in another thread that CanAutM3 is now running a square setup with 275's.

My instructor recommended running a square setup if I can, so I can rotate tires.

Any updates or opinions?

My street setup (which also is my wet track setup) is the 275-295/35R19 PSS on the OEM 19" rims.

My track setup is the square one; with 275/35R18 NT01 shod on Apex EC-7 18x10ET25 wheels. I run a square setup at the track to better balance tire wear, but the S55 has so much torque, that I am waiting for Apex to release a proper fitting 18x11 EC-7 and considering going with 305/35R18 in the rear.

If you encounter that much "push" that scrubs off too much of your speed, it gives me the feeling that you are overdriving the car. The F8X is pretty neutral from the factory (as opposed to the E92 and E46 M3s). Try the famous slow-in-fast-out approach, smooth is fast

.

Regarding brakes, while I was surprised how decently they performed at the track for street pads, the OEM pads are just that: street pads. You might want to consider going with a proper track pad. It will end up costing you less because they will last much longer at the track while giving you better brake performance.

Even in MDM, the stability system is very intrusive. But again, if you struggle to accelerate out of corners at the beginner level, it tells me that you are overdriving the car. Try a little throttle modulation and don't forget to open the steering before applying more throttle. You may want to consider coding Euro-MDM, it is a huge improvement over the US-MDM.

The PSS are just not a proper dry track tire for the F8X. When pushed just a little, the outer tread block start to melt and chunk away. IMO, going to a larger size will not change much of that. You should consider AD08R, RE71 or NT05 for example, which are pretty good non-r-compound tires for the track.

Do note that if you go with a square setup, MDM (even Euro-MDM) well get seriously in the way with constant and useless interventions. Running DSC off will be the only real option, which does involve more risk (but way more fun

).

My M4 wearing it's track clothes

:

Jadski · 06-23-2015, 05:00 AM

Car looks great! Thanks for the info. Very helpful. You are totally right about overdriving. My instructor and I had a lot of conversation about that. By the end of the weekend, I was much smoother. But once those PSS's got hot on a hot track, it was like there was butter on them.

Probably going with the staggered setup you recommended for DD/wet track. I'll have to price out an extra set of the apex square setup.

Thanks again

RocketBoots · 06-24-2015, 02:26 PM

Great to see this thread has gotten a lot of traction :P

I'm really surprised how good the 275/295's look. Fills out the wheel well nicely, pushes the tire out, and the extra rubber looks more race car IMO. Although, I got distracted a little by the MPE...

OP, I was surprised to hear your observations about wet traction, especially given you had OE tires vs generic (with the wider water channels). I assume you've driven through similar puddles with the stock MPSS and not had this issue??

Also, as your wet track setup, have you had a chance to use the 275/295 setup on the wet track yet?

Great thread. I'm thinking I'm gonna go with the 275/295/35 setup, and sooner rather than later by just moving the rears up front and getting the M5's tires for the rear.

BTW, I think they paint SilverStone a different color for Canada; it looks so silver, and so good

ssabripo · 06-24-2015, 02:39 PM

CanAutM3, any updates on your hydroplaning issues?

DBV · 06-26-2015, 01:55 PM

Quote:

Originally Posted by CanAutM3

Pics as requested:

Stock suspension and no spacers.

That looks spot on. I think this setup plus the Eibach Pro Kit (when it becomes available) will look fantastic, plus actually be functional. How much room do you find left for spacers? I know you're not a fan of them, but in the name of science, inquiring minds want to know!

CanAutM3 · 06-26-2015, 03:50 PM

Quote:

Originally Posted by DBV

That looks spot on. I think this setup plus the Eibach Pro Kit (when it becomes available) will look fantastic, plus actually be functional. How much room do you find left for spacers? I know you're not a fan of them, but in the name of science, inquiring minds want to know!

IMO, there is room for spacers in the rear, probably up to 12mm would fit guessing from distance to the fender. In the front, I am not so sure. Since the 275/35 are both taller and wider than the 255/35, they do come very close to the fender liners when steered. They would likely rub with spacers. Maybe 5mm would work, but I am pretty sure anything more would rub...

CanAutM3 · 06-26-2015, 04:03 PM

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Originally Posted by ssabripo

CanAutM3, any updates on your hydroplaning issues?

I would not call it an "issue" per se. The car is still drivable and safe in the wet with the 275-295/35R19 setup. It is just more sensitive to standing water than the OE setup. It is all a question of compromise, this setup favors dry grip over wet (standing water) grip.

I am guessing it is a reason why BMW did not go with wider contact patches on the F8X, to ensure better wet performance.

I am still very happy with this setup though

.

ssabripo · 06-26-2015, 06:01 PM

Quote:

Originally Posted by CanAutM3

I would not call it an "issue" per se. The car is still drivable and safe in the wet with the 275-295/35R19 setup. It is just more sensitive to standing water than the OE setup. It is all a question of compromise, this setup favors dry grip over wet (standing water) grip.

I am guessing it is a reason why BMW did not go with wider contact patches on the F8X, to ensure better wet performance.

I am still very happy with this setup though

.

Thanks!

ssabripo · 07-03-2015, 02:01 PM

So guys, I just ordered the 295/35 PSS tires, and had a call from tirerack insisting the tire is not a good choice due to the big increase in diameter... I explained some of the points in this thread, etc, and kept the order anyway.

Having said that, does anyone have an idea on how the speedometer readings are affected by this 275/295 /35 setup?

CanAutM3 · 07-03-2015, 02:07 PM

Quote:

Originally Posted by ssabripo

So guys, I just ordered the 295/35 PSS tires, and had a call from tirerack insisting the tire is not a good choice due to the big increase in diameter... I explained some of the points in this thread, etc, and kept the order anyway.

Having said that, does anyone have an idea on how the speedometer readings are affected by this 275/295 /35 setup?

About 2%.

So that means that my speedometer is now 2% MORE accurate

.

CanAutM3 · 07-03-2015, 02:18 PM

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