[Hiddenknife]

Hi everyone,

I wanted to share with you my recent discovery that seemed to have no fix until i did something which i should have done from the beginning.

A while back, after i bought an X4 M40i 2020 in February i decided to ditch the OEM runflats (pirelli Pzeros) because they were worn. I did run on them like 1000kms but had not paid any attention to how the vehicle was running because i did not feel anything wierd. Later on i bought some nice summer Michelin Pilot Sport 4 s (non star marked, non runflat) tires. After a few months i did start to notice the car was behaving wierd when accelerating hard from almost a standstill or low speed rolling. It felt like a wierd judder/knock like feeling when changing the gears, every time, most noticed in Sport + because the car has full power there. Also on the corners the car was balancing way more than with the runflats, a floating like feeling. (maybe because they were non runflats) and last, when backing with the wheel on full lock either right or left there was a wierd noise coming from the wheels (thicking on metal like) and the tires were like skipping when cornering on full lock at low speeds.

I mostly observed the later two issues since September. Now in December i ordered a pair of OEM Runflats for winter (pirelli winter sottozero 3) because i thought those issues were related to the tires, mostly because the Rolling Circumference in non OEM tires is not most friendly to BMW's xDrive. The tires maybe having the same size but if you put an OE tire side by side a non OE tire of the same size, THEY ARE ACTUALLY NOT THE SAME SIZE. I did compare this and the non OE tire is smaller in diameter, at least that was the case i tested.

Went to the dealership today to mount the new tires and guess what. Surprise, all of the issues i had are COMPLETELY GONE! I did believe that all that "star marking" bullshit was just marketing but it's actually not, at least in my case. Many people told me to ditch the OE runflats because they handle bad, but actually the car handles better than with the NON OE tires because i feel the steering is more sharp and the car feels more planted in corners due to sidewalls being stiffer. I guess BMW made the car with runflats in mind so they adapted the suspension accordingly. When running the non runflat tires the car felt very squishy and did not give me confidence at all in corners.

I want to mention i made this post just in case someone has xdrive judder, tire skipping when full lock cornering and things like that. I did not praise the OE tires before as i''ve said because i thought its all BS, but it seems for 4x4 cars especially with staggered setups its very sensitive to those things. I just hope i didnt do any damage to the Transfer Case running the non star marked non runflat tires.

If you had those problems or similar ones, please rethink your tires first just not to sped a fortune buying another transfer case.

P.S.: All tires were checked before removing and all were within 0,2 mm difference so i could not have been that. Also the tires were perfectly fine from factory, all had same RC when compared

[BeEmVe]

There is an adage that correlation does not imply causation.

I don't agree with your statement that the rolling circumference in non OEM tires is not most friendly to BMW's xDrive. The issue with all wheel drive vehicles is that one wants all of the tires to have the same circumference. Sounds like the summer tires met that condition.

The biggest change with a set tires with a slightly different rolling circumference will be the speedometer and odometer reading.

That said tires of different types with the same base sizing can have a difference in rolling circumference. It might not be much difference but there can a difference. I did a random selection of tires from four different mfg. that are 225/45R17 the revs. per mile were listed at: 835, 832, 833, 831.

That said, suspensions are set for run flat tires so certainly running go flats will have some affect such a softer ride.

At the end of the day changing tires improved the handling but I would not base it solely because of OEM * tires. Probably a combination of small changes, new tires, run flat (stiffer), winter (softer rubber), etc.

The question is come spring what are you going to run?

[Hiddenknife]

Originally Posted by BeEmVe

There is an adage that correlation does not imply causation.

I don't agree with your statement that the rolling circumference in non OEM tires is not most friendly to BMW's xDrive. The issue with all wheel drive vehicles is that one wants all of the tires to have the same circumference. Sounds like the summer tires met that condition.

The biggest change with a set tires with a slightly different rolling circumference will be the speedometer and odometer reading.

That said tires of different types with the same base sizing can have a difference in rolling circumference. It might not be much difference but there can a difference. I did a random selection of tires from four different mfg. that are 225/45R17 the revs. per mile were listed at: 835, 832, 833, 831.

That said, suspensions are set for run flat tires so certainly running go flats will have some affect such a softer ride.

At the end of the day changing tires improved the handling but I would not base it solely because of OEM * tires. Probably a combination of small changes, new tires, run flat (stiffer), winter (softer rubber), etc.

The question is come spring what are you going to run?

Im selling my MPS4s and buying some OEM runflats (either Pirelli PZero or Michelin Latitude Sport 3) as they are * marked variants. Im not willing to take any more risks because its not something of guessing, its something that has happend and was fixed when used the correct tires. I ve read a similar post a while back from some guy with the same issue and it was solved when he used the OEMs. I wasnt a fan of OEM runflats until my ride became worse after using non runflat non star marked tires (and i wanst runing Ling Longs, but Michelins) i guess if i want non runflats i have to buy another car that is designed with those in mind, the latest X3 for example.

[ShocknAwe]

Tires from manufacturer to manufacturer can't be compared in size or tread wear. The only thing that is consistent is diameter.

You need to compare measured circumferences.

That said, I think you have something else going on, and your observation is spurious.

Very possible your Mich tires had a defect as well. It happens.

[Mavus]

many people run non * spec summer, all season, winter rubber without issues. I have winter tires non * spec on two cars now and no issues over the years. There is nothing magical about * spec tires.

Most likely you either had defective tire(s) or your suspension has an issue or you bought wrong size and had mismatched tires.

[Hiddenknife]

Originally Posted by ShocknAwe

Tires from manufacturer to manufacturer can't be compared in size or tread wear. The only thing that is consistent is diameter.

You need to compare measured circumferences.

That said, I think you have something else going on, and your observation is spurious.

Very possible your Mich tires had a defect as well. It happens.

exactly, buying non OE tires doesnt guarantee you perfect match between all 4 tires rolling circumference. I gues i lost fhe lottery on my summer set. That s the point with those OE tires, the manufacturer of the car gives some clear instructions to tire producers on how they should be made to match different staggered setups. The thing is it solved my issue, im happy and nothing else matters. I made this post for the people who have similar issues and want an easy fix. Buying non OE tires is fine for cars without 4x4 or non staggered setups but for those who have 4x4 and staggered its more tricky.

[RockCrusher]

Originally Posted by Mavus

many people run non * spec summer, all season, winter rubber without issues. I have winter tires non * spec on two cars now and no issues over the years. There is nothing magical about * spec tires.

Most likely you either had defective tire(s) or your suspension has an issue or you bought wrong size and had mismatched tires.

Many or at least some do run non spec tires -- summer, all season, winter -- without any issues.

But I have come across a number who have reported issues.

It is my feeling tires are too expensive to gamble non spec tires will be ok. I buy spec tires -- over the years lots of spec tires -- and have experienced no differences. The first Pirelli tires my Boxster came with and the last set of Pirelli I put on the car felt the same and that was about 16 years between the two sets of tires and 300K+ miles. Same with my other Porsche.

So far have not had to buy new tires to replace worn out tires for any BMW but when the time comes you can be sure I'm buying spec tires.

I don't like to mess with success or fix what ain't broke...

[Mavus]

Originally Posted by RockCrusher

Many or at least some do run non spec tires — summer, all season, winter — without any issues.

But I have come across a number who have reported issues.

It is my feeling tires are too expensive to gamble non spec tires will be ok. I buy spec tires — over the years lots of spec tires — and have experienced no differences. The first Pirelli tires my Boxster came with and the last set of Pirelli I put on the car felt the same and that was about 16 years between the two sets of tires and 300K+ miles. Same with my other Porsche.

So far have not had to buy new tires to replace worn out tires for any BMW but when the time comes you can be sure I'm buying spec tires.

I don't like to mess with success or fix what ain't broke...

There is no gamble. If your car is not running properly ie driving smooth with non * spec tires of stock sizing there is an issue with the car. I switch from Mich * spec to non * spec Bstone snows and the car is smooth with both sets. Mich are 19” and Bstones 18”.

[RockCrusher]

Originally Posted by Mavus

There is no gamble. If your car is not running properly ie driving smooth with non * spec tires of stock sizing there is an issue with the car. I switch from Mich * spec to non * spec Bstone snows and the car is smooth with both sets. Mich are 19” and Bstones 18”.

I dare say if I fitted non spec tires on my new BMW and there was a problem and I took it in the dealer could refuse to look at the car or at least look at it under its new car warranty -- being in my case the car is not even a month old -- due to the presence of tires not sanctioned by BMW.

However, had I even had plans to non spec tires I'd first drive the car enough to confirm that with the spec tires the car was not manifesting any issues.

So if the car manifested any issues I would have a high degree of confidence it was the tires.

But I just don't feel any desire to experiment with using non spec tires.

I didn't buy the new car with the thought that all it needed to be perfect, or just better, would require me to run non spec tires.

Non spec tires don't have to manifest any untoward behavior to be wrong for the car. Back in 2009 I bought a German sports are with AWD and a staggered wheel/tire setup. The factory had some guidelines regarding front and rear tire diameter differences. Go outside of the allowable tire diameter differences and the viscous fluid coupling used to transmit torque from the rear axle to the front axle was at risk of damage.

My current BMW (M8) is AWD. I will stick with using spec (Star) tires to avoid putting the AWD system at risk of damage.

'course it is my car and I can do that if I want.

The flip side is one can choose to do something else. While one can do that I don't recommend it. I don't like to recommend going rogue with tires and counting on the person having the same good luck as the person -- there's always one -- that swears non spec tires are great, harmless, and has never had any problems.

[Mavus]

Originally Posted by RockCrusher

I dare say if I fitted non spec tires on my new BMW and there was a problem and I took it in the dealer could refuse to look at the car or at least look at it under its new car warranty — being in my case the car is not even a month old — due to the presence of tires not sanctioned by BMW.

However, had I even had plans to non spec tires I'd first drive the car enough to confirm that with the spec tires the car was not manifesting any issues.

So if the car manifested any issues I would have a high degree of confidence it was the tires.

But I just don't feel any desire to experiment with using non spec tires.

I didn't buy the new car with the thought that all it needed to be perfect, or just better, would require me to run non spec tires.

Non spec tires don't have to manifest any untoward behavior to be wrong for the car. Back in 2009 I bought a German sports are with AWD and a staggered wheel/tire setup. The factory had some guidelines regarding front and rear tire diameter differences. Go outside of the allowable tire diameter differences and the viscous fluid coupling used to transmit torque from the rear axle to the front axle was at risk of damage.

My current BMW (M8) is AWD. I will stick with using spec (Star) tires to avoid putting the AWD system at risk of damage.

'course it is my car and I can do that if I want.

The flip side is one can choose to do something else. While one can do that I don't recommend it. I don't like to recommend going rogue with tires and counting on the person having the same good luck as the person — there's [...]

yeah of course use whatever tires you want just like the rest of us just don’t claim that the car somehow knows or reacts differently btw those two tire specs. star spec simply means it meets certain design criteria that bmw wants for rubber performance and wear. the secret sauce is in the rubber chem, tire structure, manuf process and tread patterns developed by tire manuf.

if you take your M8 to track you’d most likely use non * spec tires and the car will be perf fine. you can even ask bmw to confirm.

here is a tire for g30 540xi that is tuned for mb and bmw but can work on other cars also

[pbonsalb]

Reportedly, BMW uses non star spec Continentals instead of star spec Michelin P4S on its M5 driving school cars. Those cars are sold by BMW with warranty after a year or so.

[Hiddenknife]

Originally Posted by Mavus

yeah of course use whatever tires you want just like the rest of us just don’t claim that the car somehow knows or reacts differently btw those two tire specs. star spec simply means it meets certain design criteria that bmw wants for rubber performance and wear. the secret sauce is in the rubber chem, tire structure, manuf process and tread patterns developed by tire manuf.

if you take your M8 to track you’d most likely use non * spec tires and the car will be perf fine. you can even ask bmw to confirm.

here is a tire for g30 540xi that is tuned for mb and bmw but can work on other cars also

Its not just about the rubber compound, its about rolling circumference being the same using spec tires. Non spec tires have a bigger % variation in RC from factory than spec tires. Its like a lottery. To swear by non spec tires that are just as good, is slighly misleading. You can obviously get a good set with very close RC with non spec tires but there s that bigger or lessser chance you get some uneven rolling circumference tires with non specs than in the end will only create problems for drivetrain/xdrive.
Everyone is free to buy what they want but if you want to be 100% safe it's the spec tires. Of course you can might aswell have non spec tires with any issues and claim them the best but thats because you got the right ones. I even talked to an production manager employee at Continental tyres and confirmed me just this! (this was in the summer before i noticed my issues).

I would recommend everyone who is looking to be problem free go the route i went. Dont gamble. Why waste money and eventually get a bad set with uneven RC when you can be on point from the beggining. I got not one but 3 issues fixed just because of the tires, and i repeat i was using the premium Michelin Pilot Sport 4s not some cheapies.

I dont look to argue with anyone because for me its not even a situation of if's and but's. I went through some problems and this fixed them. I got my car checked before that at the dealership and they didnt find any prior issue, so i had to be the tires, and it was!

[Mavus]

Originally Posted by Hiddenknife

Its not just about the rubber compound, its about rolling circumference being the same using spec tires. Non spec tires have a bigger % variation in RC from factory than spec tires. Its like a lottery. To swear by non spec tires that are just as good, is slighly misleading. You can obviously get a good set with very close RC with non spec tires but there s that bigger or lessser chance you get some uneven rolling circumference tires with non specs than in the end will only create problems for drivetrain/xdrive.
Everyone is free to buy what they want but if you want to be 100% safe it's the spec tires. Of course you can might aswell have non spec tires with any issues and claim them the best but thats because you got the right ones. I even talked to an production manager employee at Continental tyres and confirmed me just this! (this was in the summer before i noticed my issues).

I would recommend everyone who is looking to be problem free go the route i went. Dont gamble. Why waste money and eventually get a bad set with uneven RC when you can be on point from the beggining. I got not one but 3 issues fixed just because of the tires, and i repeat i was using the premium Michelin Pilot Sport 4s not some cheapies.

I dont look to argue with anyone because for me its not even a situation of if's and but's. I went through some problems and this fixed them. I got my car checked before that at the dealership and they didnt find any prior issue, so i had to be the tires, and it was!

it’s just a discussion and always feels good to fix issues no question! it’s also beneficial to community when we isolate specific problem and now exactly how it was resolved.