My new favourite term!!!
Used 17k BMW needs 15k in repairs within days
- Thread starter Joe1
- Start date
You mean having four guitars isn't enough?
Ok, so if you own G05 or whatever, and put bigger tires that are allowed per manual, there will be a small discrepancy in diameter.
So how does TC survives that? How does then that sensor reacts?
If TC fails let’s say bcs. small discrepancies between two different type of tires in 225/45 R17 size, then TC would bomb at let’s say staggered set up 225/40 R18 in front and 255/35 R18 in the back and car came with 225 45 R17. Both set ups are allowed per manual, but there is small discrepancy between them, definitely bigger than discrepancy between tires of two different manufacturers in same size.
I would really like someone with better knowledge how TC works to chime in about this.
Last edited:
Of course.
But that is not the what we talked about. It is bombing transfer cases bcs. let’s say owner used Michelin PSS from Costco, instead of Bridgestone DriveGuard from BMW with star spec.
I am having hard time with that.
I could have worded that better, but I was replying about an AWD BMW - and I'll bet THOSE came with RunFlats.
Keep in mind the requirement came down from BMW Canada after they had already replaced 2 transfer cases. I suspect the customer was abusing the vehicle in some way and the tire requirement was BMW Canada putting the owner on notice. It's not like the customer has returned again with another blown transfer case.
That is my suspicion. BMW is washing hands or customer is at fault. But, discussion was that non-approved tires are going to bomb any transfer case.
That used to be the case, but now regular tires are available on some xDrive models- primarily M Performance and M cars.
Yes, and on all I think you have option of spare tire.
So I talked to BMW master tech I know.
It is bit more complicated than it seems.
@mightymousetech is right that BMW wants approved tires and that TC damage can happen due to not using approved tires.
But there is more to it. BMW basically wants quality control over production and all tires have to be within 1/4 of an inch of their diameter. However, the real reason why this could be an issue is using Ling Long, Mucho Macho etc. brands. Seeing bigger discrepancies in diameter from reputable tire manufacturers is highly unlikely. Also, even if there is discrepancy between Ling Long and BMW approved tires, it is important that 4 Ling Long tires are within 1/4 of an inch between each other.
@CapriRacer maybe can chine in about discrepancies among reputable companies like Michelin, Bridgestone etc?
But he argues that biggest issue he sees is people changing two tires etc. and issues with staggered set up and one axle wearing too much compared to other one.
It is bit more complicated than it seems.
@mightymousetech is right that BMW wants approved tires and that TC damage can happen due to not using approved tires.
But there is more to it. BMW basically wants quality control over production and all tires have to be within 1/4 of an inch of their diameter. However, the real reason why this could be an issue is using Ling Long, Mucho Macho etc. brands. Seeing bigger discrepancies in diameter from reputable tire manufacturers is highly unlikely. Also, even if there is discrepancy between Ling Long and BMW approved tires, it is important that 4 Ling Long tires are within 1/4 of an inch between each other.
@CapriRacer maybe can chine in about discrepancies among reputable companies like Michelin, Bridgestone etc?
But he argues that biggest issue he sees is people changing two tires etc. and issues with staggered set up and one axle wearing too much compared to other one.
First, there is no regulation that requires a tire manufacturer to produce a tire to a given dimension. That means that Brand X tires may be quite different in diameter than Brand Y even if the size is the same.
This has caused quite a few problems - one being that sometimes tires rub where a different make/model doesn't. Another is the differential problem being discussed above.
Further, there is no regulation that a tire manufacturer must produce tires within a certain tolerance, even if there is no target value. That means that even within a given manufacturer, not only could different models have different diameters for the same size, but even within a given model, it might be quite different. I know of one instance where the same make/model/size produced in different plants produced tires of different diameters such that it damaged an AWD system. The good news is that the tires were NOT installed in a set of 4 BY THE VEHICLE DEALER, so the dealer picked up the repair cost.
So back to the problem above. I can understand BMW requiring Star Spec tires if they are going to pick up the repair cost for a failed AWD system! The lesson here is that if you own a BMW with an AWD system, use Star Spec tires or be prepared to absorb any related repair costs. [[ Note to self: Remind daughter!! She has a BMW X3.]]
Would that fly in the US with the M&M Act?
I assume you mean the Magnuson-Moss Act, a Federal Law which regulates the way warranties are handled in the US. Wikipedia: Magnuson-Moss Warranty Act
Obligatory Disclaimer: I am not a lawyer. I have worked with lawyers in this area, so take this for what it's worth.
There are 2 issues:
1) The company can't just deny warranty coverage. They have to tell you why they are denying coverage. Some people think that means they have to prove that you did something wrong, but that is incorrect. They just have to provide a reason.
2) The act says that the company can NOT require branded parts. The issue here is that a "Star Spec" is not really a branded part, although a good lawyer could make an argument that it is as effective as a branded part.
How does this apply to this situation? If the drivetrain were to fail within the warranty period, the company (We are talking BMW here, but it would apply to Subaru, GM, Ford, etc.) the company must either cover the damage according to the warranty (which might include only parts, not labor - or some other funny clause) OR tell the customer WHY they are denying coverage. In this case, they could point to Non-Star Spec tires - and their rationale would be that they KNOW Star Spec tires have a diameter tolerance that is within the tolerance of the drivetrain, but they do NOT know that for any other tire spec.
The burden of proof would then shift to the customer - who is ill equipped to provide a documentation as a counter argument. If I were BMW (or whoever), I would then concede to pay half the cost.
The "branded part" argument? BMW (or whoever) is NOT denying coverage due to the branded part. They are denying coverage because of diameter tolerance. They are merely saying that a Star Spec tire is within the tolerance and not accepting that a Non-Star Spec tire is not until proven otherwise.
On that last bit. I think the owners manual only specifies a tire size not a tolerance within the approved sizes.
I think BMW is trying here to keep people in line with reputable tires.
The person I talked to is arguing that really is not an issue at all. Where the issue is are mismatched tires, people not rotating tires, and staggered set up where one axle wears out faster and they neglect to react in time.
This is from practice. Their TC is not anymore sensitive than others with similar set up. I guess they just went step further to make sure it doesn’t happen under warranty.
The person I talked to is arguing that really is not an issue at all. Where the issue is are mismatched tires, people not rotating tires, and staggered set up where one axle wears out faster and they neglect to react in time.
This is from practice. Their TC is not anymore sensitive than others with similar set up. I guess they just went step further to make sure it doesn’t happen under warranty.
And it’s not just BMW with Star-spec and RSC markings, Mercedes has MOE/MOE Extended, Audi/Porsche has a marking too(but not VW, I think A0/N-Spec) - but GM started OE-level tire certification with the TPC specs(hence why OE GM tires have a TPC-spec number on them).
If there’s one thing that drives me up the wall, it’s Chinese tires. It tells me the owner or driver doesn’t care. If you’re Hertz/Enterprise(Enterprise is more than just rental cars - they are one of the biggest fleet management companies out there as well, and of course they will spec Chinese tires and Jiffy Lube/Firestone for “maintenance” for their fleet accounts) or a fleet manager/Uber driver or if the car is on its last legs with a final destination of Copart/Pick & Pull that’s one thing but when I see LingLong/Sailun/Westlake/etc especially on a “nice”/newer car, it tells me you don’t care and do the absolute minimum of maintenance/repairs.
Precisely!
Since I can’t edit my post anymore, there are situations where a Chinese tire is appropriate - such as the now increasingly harder to find 185/70-14, 195/70-14, 205/70-15, 215/70-15 and any 75-aspect ratio passenger tire. The tier 1 brands are phasing those out.
From that I’ve read here, Milestar seems to be the better of the Chineseium.
I know I'm a little late to this thread. My theory on "star spec" and TC issues is that this is a much more important factor on vehicles with a staggered wheel package.
So if an F10 has 245/45ZR18 front and 275/40ZR18 in the rear, the "star spec" versions of these sizes from a given manufacturer will ensure that the rolling radius is within tolerance of each other for the TC life. You can use all the tire size calculators you want to determine that those two sizes *should* be close, but there are always manufacturing and design tolerances.
Years ago I had a 1992 Porsche with a staggered set up. Long story short I went with +20mm wider tire sizes using calculators and experience from others online and it turned out that for the S-02 PP tires, Bridgestone made the size I had on the rear "short" for the spec and the size I had on the front "tall" for the spec. Other brands/models of tire in the same sizes on the same car didn't show this difference. It was visibly odd looking, but "should have been fine" according to tire size calculators. It was RWD so nothing was ruined, but it illustrated that specs and calculators don't always tell the whole story.
"Star spec" can mean other things too. Back in the mid-2000s my E39 was cupping/feathering/heel-toe wear on the outside edges of UHP tires on the front. I think I had Toyo T1S at the time. In working with a Toyo regional manager and a few other resources, I came to learn that "star spec" tires all had connected outside tread blocks specifically to combat heel/toe wear from BMW sport suspension of the day, and led to fewer noise complaints as tires wore in. Tires like the T1S with disconnected tread blocks got very noisy very quickly. Toyo revised the the design with the T1R to have a solid band near the outside tread blocks which solved this problem. Star spec sport package tires of the day had this all figured out already. I believe there was an example of a tire which had disconnected tread blocks in non-star spec, but connections between the tread blocks on the star spec version.
It's not always a scam.... That being said, none of my current tires are star rated, but I am running a square setup.
So if an F10 has 245/45ZR18 front and 275/40ZR18 in the rear, the "star spec" versions of these sizes from a given manufacturer will ensure that the rolling radius is within tolerance of each other for the TC life. You can use all the tire size calculators you want to determine that those two sizes *should* be close, but there are always manufacturing and design tolerances.
Years ago I had a 1992 Porsche with a staggered set up. Long story short I went with +20mm wider tire sizes using calculators and experience from others online and it turned out that for the S-02 PP tires, Bridgestone made the size I had on the rear "short" for the spec and the size I had on the front "tall" for the spec. Other brands/models of tire in the same sizes on the same car didn't show this difference. It was visibly odd looking, but "should have been fine" according to tire size calculators. It was RWD so nothing was ruined, but it illustrated that specs and calculators don't always tell the whole story.
"Star spec" can mean other things too. Back in the mid-2000s my E39 was cupping/feathering/heel-toe wear on the outside edges of UHP tires on the front. I think I had Toyo T1S at the time. In working with a Toyo regional manager and a few other resources, I came to learn that "star spec" tires all had connected outside tread blocks specifically to combat heel/toe wear from BMW sport suspension of the day, and led to fewer noise complaints as tires wore in. Tires like the T1S with disconnected tread blocks got very noisy very quickly. Toyo revised the the design with the T1R to have a solid band near the outside tread blocks which solved this problem. Star spec sport package tires of the day had this all figured out already. I believe there was an example of a tire which had disconnected tread blocks in non-star spec, but connections between the tread blocks on the star spec version.
It's not always a scam.... That being said, none of my current tires are star rated, but I am running a square setup.
Last edited:
Similar threads
