Tire Scientist Needed!

[Sandmansc]

I could be a wheel man, but I don't know much about the science behind tires. There. I said it. That's why I need your help.

I have owned 6 328i and 335i's and all had a different aspect ratio ie. 225/35/19 front 255/30/19 rear.

I bought my first ///M. It's amazing.

It came with ZITO ZF01
19x10 265/35/19
19x11 305/30/19
The continental tires slid constantly.

I just replaced them with PS4S using the exact same setup.

1. Rubbed rear fenders. Had the car lowered. Rolled fenders. Realigned. No more rub.

#######

2. Here's the problem.

— Traction OFF.
Little scary in the twisty tight smoky mountains where I live at Deals Gap aka the Dragon.
But it's amazing.

— Traction ON
My wheel spin light flashes when I corner when at 0 throttle. Wheel spin light flashes even at 140mph in a straight.

— MDM ON
Same. Kills my power. Even after apex and in a straight it has low power.

The wheels are not spinning.


It's been suggested that I have a bad ABS Sensor. How does that happen? Something they may have done mounting tires? Easy fix? Can a local shop handle this or take to dealer?

Someone else said it's all because my aspect ratios are different when they should be the same.

I looked up the stock tire specks for an F80 and while he is correct they do come with 35mm front and rear... that doesn't explain why the Continentals had no issue and the Michelin's do. Surely these cars can run a 35 front 30 rear without a problem?!


Lastly. When these tires are shot next month....what size tires should I get ????

Been a member for years you guys are always extremely helpful. Thanks in advance !



Edit. I'm not sure if it's relevant but thought it may be needed.

Mods
SSR intakes
VRSF Chargepipes
VRSF Catless Downpipes
AA Catless Midpipe
BM3 Stage2 OTS 93
H&R SuperSport Springs
ZITO ZF01 as listed in post

[aswy6]

I thought that there might be something weird until i saw Catless Downpipes and BM3. I mean i would not expect to be able to put over 500whp to just two patches of tires a with a width of A4 sheet of paper. Unless you going to put some 200 thread tires on there and let them warm up, i would not expect to hook up right away

[LOW4LYF]

Just out of curiosity... what did you rolled on your fenders? There's nothing to roll at all.

[rborane]

MP4S in 265/35 and 305/30 have the exact same diameter of 26.3".

Factory diameter is 26" front and 26.6" rear with 255/35/19 and 275/35/19.

If I were to guess, it may have to do with running the same diameter front and rear and potentially throwing the DSC off because of it. The best bet is to try and keep the diameter difference between front and rear as close to factory as possible, or at least keep the rear diameter greater than the front to prevent any DSC issues. Sounds like maybe a wire could be a factor as well during install. I would run 275/30/19 & 295/30/19 as those diameters in a P4S is 25.6" and 26". You can also keep the 305/30 which is 26.3" and switch the front to a 275/30.

Good luck

[DanMpower]

Originally Posted by LOW4LYF

Just out of curiosity... what did you rolled on your fenders? There's nothing to roll at all.

This was my same thought...

[Sandmansc]

Originally Posted by rborane

MP4S in 265/35 and 305/30 have the exact same diameter of 26.3".

Factory diameter is 26" front and 26.6" rear with 255/35/19 and 275/35/19.

If I were to guess, it may have to do with running the same diameter front and rear and potentially throwing the DSC off because of it. The best bet is to try and keep the diameter difference between front and rear as close to factory as possible, or at least keep the rear diameter greater than the front to prevent any DSC issues. Sounds like maybe a wire could be a factor as well during install. I would run 275/30/19 & 295/30/19 as those diameters in a P4S is 25.6" and 26". You can also keep the 305/30 which is 26.3" and switch the front to a 275/30.

Good luck

That helps. Thanks. Which one would you do ?

[Sandmansc]

Originally Posted by LOW4LYF

Just out of curiosity... what did you rolled on your fenders? There's nothing to roll at all.

Part plastic part metal if I understood correctly. I'll take closeup pics.

Has a little more room to stretch but it would stand out even more.

[Sandmansc]

Originally Posted by Sandmansc

Part plastic part metal if I understood correctly. I'll take closeup pics.

Has a little more room to stretch but it would stand out even more.

Trying to upload again...

[Ropes]

US MDM might as well be full stability/traction control on. Have you coded the GTS MDM? That allows for quite a bit more slip angle before engaging. The GTS diff coding helps quite a bit too.

[Sandmansc]

Originally Posted by Ropes

US MDM might as well be full stability/traction control on. Have you coded the GTS MDM? That allows for quite a bit more slip angle before engaging. The GTS diff coding helps quite a bit too.

No but I've heard about Euro MDM. Same thing ? If not which is better.

Second... how do I do this ??

[F3IGHTY]

Originally Posted by rborane

MP4S in 265/35 and 305/30 have the exact same diameter of 26.3".

Factory diameter is 26" front and 26.6" rear with 255/35/19 and 275/35/19.

If I were to guess, it may have to do with running the same diameter front and rear and potentially throwing the DSC off because of it. The best bet is to try and keep the diameter difference between front and rear as close to factory as possible, or at least keep the rear diameter greater than the front to prevent any DSC issues. Sounds like maybe a wire could be a factor as well during install. I would run 275/30/19 & 295/30/19 as those diameters in a P4S is 25.6" and 26". You can also keep the 305/30 which is 26.3" and switch the front to a 275/30.

Good luck

This - I had the same issue running 315/30-18 square. The DSC expects staggered wheel speeds, otherwise the car thinks something is slipping.

[LOW4LYF]

Plenty of people running the same tire front and rear without any issues, myself included.

Staggered setup is not necessary. Even BMW is selling a square set-up.

[knightarmor]

My F80 prefers square or close to it. With factory 19" sizes it was straight up power loss in tight twisties and scary power cutoff at speed. Running square or with 265/275's it's difficult for me to get the traction control to even come on.

[Sandmansc]

So should I switch to a 275/30/19 - 295/30/19 ?

[rborane]

Originally Posted by Sandmansc

So should I switch to a 275/30/19 - 295/30/19 ?

Yes. Or keep the 305 and try 275/30 in front with it

[TopJimmy]

I don't think it's your aspect ratios or tires really. You're running OTS Stage 2 and it sounds like you haven't coded for Euro MDM yet. I run a BPMSport Stage1 custom (about 100HP) and Euro MDM is a must. It allows for a lot more "play" than our USA MDM. The MDM settings require "coding" instead of the "flash" that is your tune.

DSC On is only for Efficient Mode...when driving the wife. At Stg1 and up DSC Off is really just for donuts or drifting.

Maybe see if 325s fit out back to maximize tread (last resort, try the MDM first). Keep those 265s up front if they grip now (even though they're specced for a 9.5). I run 275 fronts and they feel heavy. Maybe work fine for your front 10s, since 275s are specced for 10s.

Regardless of tire width or aspect ratio try to stick with a tire with a 26-26.6in diameter, which still allows lowering with most mild-medium drop spring kits. Heavier drops may need -cambering to clear fender lips. HAS kits give flexibility for fitment.

Stay cool, stay safe,
-TJ

[rborane]

I would definitely recommend purchasing the THOR app and using the dynamic package, which includes GTS MDM, CS MDM, and Euro MDM. Go with GTS MDM in my opinion.

If you are getting DSC warning mid corner with no throttle input, or it is flashing when going straight, that indicates a tire diameter issue front to rear. Euro MDM and GTS MDM increases slip angle compared to US MDM which is overly intrusive.

[Sandmansc]

Appreciate the input.

There's a post on here that the euro and gts MDM of today is about the same restriction as the us version ?

The 305 rear was fine with continental but w the PS4s being meatier it rubs. So I rolled fenders. I lowered it w H&R SS springs 1.3/0.8.
That makes me really scared to stick a 275 on the front. Thinking a 295/30/19 or a 295/35/19. Not even sure which of those to get. The guy who owns ZITO wheels says he's set up more M3s with the 305/30-265/35 combo than he can count. Not clue why mine shows wheel spin and rubs.

[rborane]

What are the offsets?

[Sandmansc]

Originally Posted by rborane

What are the offsets?

Sorry this would have helped in the original post huh ?

19x10 ET25
19x11 ET35

[LOW4LYF]

Originally Posted by Sandmansc

Sorry this would have helped in the original post huh ?

19x10 ET25
19x11 ET35

11" et 35 people use usually a 295 tire, to run a 305 you would need et 4x or higher.

[Sandmansc]

Originally Posted by LOW4LYF

11" et 35 people use usually a 295 tire, to run a 305 you would need et 4x or higher.

So I have a 265/35/19 front 305/30/19 rear.
If I keep the 265/35/19 does that mean I need a 295/35/19? 35 sounds taller.

I've also been told to keep them at the right ratio or spec whatever ... 20mm difference. So if I have a 265/35 from it's recommended I get a 285/35 rear.

But that seems reeeeaaalllly stretches on my 11@ wheel.

So confused 😳😬😷