BBS wheels generate thud on acceleration

[Chicane_S54]

Originally Posted by crystalworks

How are there no pictures/specs of everything posted yet? Any hardware, wheels, tires, etc could be influencing this.

We went from 19's to 20's (with used tires) and required no TC calibration. That is until the rears wore down for about 6 months and then we started getting a "tug" or "thud" as you describe. The TC wants <1% difference in rolling diameter from front to back. New tires installed and no more problems from the TC.

As a matter of good maintenance however you could service your TC fluid (we did later) and reset the calibrations using a Foxwell NT530 or ISTA. The fluid that came out @ 85000 miles was not burnt, but it wasn't great either.

I'm not saying that you are not 100% correct because I think you are but there aren't 1000 miles on these tires with no appreciable wear or wear spots on the tires. Right now I need the TC calibration steps with ISTA. I would rather change the TC fluid and calibrate the TC before I drop $1300 for new tires.

[crystalworks]

Originally Posted by Chicane_S54

I'm not saying that you are not 100% correct because I think you are but there aren't 1000 miles on these tires with no appreciable wear or wear spots on the tires. Right now I need the TC calibration steps with ISTA. I would rather change the TC fluid and calibrate the TC before I drop $1300 for new tires.

I hear that. Just get an NT530. It costs ~$150 and does 95% of the things ISTA will do. Way handier to carry on trips and things. I use it more frequently than anything else. Though I do have Carly as well (I have owned 20+ Bimmers... so have an extensive diagnostic tool cabinet).

That said, ISTA is not hard to use once it's running. I use it with an ICOM though which adds expense. Good luck.

[Chicane_S54]

Originally Posted by crystalworks

I hear that. Just get an NT530. It costs ~$150 and does 95% of the things ISTA will do. Way handier to carry on trips and things. I use it more frequently than anything else. Though I do have Carly as well (I have owned 20+ Bimmers... so have an extensive diagnostic tool cabinet).

That said, ISTA is not hard to use once it's running. I use it with an ICOM though which adds expense. Good luck.

I have ISTA, I don't need to purchase a different unit. Do you know the ISTA procedure or no?

[crystalworks]

Originally Posted by Chicane_S54

I have ISTA, I don't need to purchase a different unit. Do you know the ISTA procedure or no?

Oh you have ISTA running.

I'll run a scan on my X5 today to get the menu tree if I have some time. It'll be under service functions, possibly under drivetrain or traction control, but I'll see what I can find.

[Chicane_S54]

Originally Posted by crystalworks

Oh you have ISTA running.

I'll run a scan on my X5 today to get the menu tree if I have some time. It'll be under service functions, possibly under drivetrain or traction control, but I'll see what I can find.

Thanks.

[Chicane_S54]

Originally Posted by ///d

The overall diameter of the fronts vs rears need to be within 1% of each other. If you get outside that 1% then you can run into issues with the traction and stability system thinking a wheel is slipping because of differences in rotating speeds.

That doesn't even make sense for 28 inch overall width on a 20" wheel/tire that would be .28 or approximately 1/4 of an inch diff. My OEMs are worn all to shit with at least that much diff and they give me zero drive-train issues.

Not to mention the vehicle hasn't kicked a single DSC or ABS code.

[crystalworks]

Originally Posted by Chicane_S54

That doesn't even make sense for 28 inch overall width on a 20" wheel/tire that would be .28 or approximately 1/4 of an inch diff. My OEMs are worn all to shit with at least that much diff and they give me zero drive-train issues.

Not to mention the vehicle hasn't kicked a single DSC or ABS code.

He's right. Anything outside 1% will cause issues. Not necessarily trigger a code either. That was exactly what I experienced when my rears wore out more quickly than the fronts (OE 20" tire sizes). What tire sizes are you running on the BBS wheels?

I scanned the truck today to get the service tree. It goes as follows in ISTA-d: Vehicle Management: Service Functions: Power train: Transmission contro unit VTG: Oil change. That will initiate the adaptation service plan. I'll post a picture tomorrow.

Edit: Here's the picture for service location

[Chicane_S54]

Originally Posted by crystalworks

He's right. Anything outside 1% will cause issues. Not necessarily trigger a code either. That was exactly what I experienced when my rears wore out more quickly than the fronts (OE 20" tire sizes). What tire sizes are you running on the BBS wheels?

I scanned the truck today to get the service tree. It goes as follows in ISTA-d: Vehicle Management: Service Functions: Power train: Transmission contro unit VTG: Oil change. That will initiate the adaptation service plan. I'll post a picture tomorrow.

Edit: Here's the picture for service location

Attachment 2949318

BBS SX's with 275/40R20 Continentals

So that boils down to approximately 1/4" of wear. Could it be the 20" wheels are more sensitive to this difference in wear than the 19's? It looks as though I am looking at getting a new set of tires. What size tires are you running on your 20's.

Are your 20's staggered? When I go to Tire rack when I select tires by vehicle every 20" setup is a staggered setup.

[Clifton]

Originally Posted by Chicane_S54

BBS SX's with 275/40R20 Continentals

May be worth running the Transfer case calibration (VTG control unit) before buying new tires.

I’m running 275/40R20 (F) and 315/35R20 (R) and recalibrated shortly after replacing them 5k miles ago.

Worth noting, Tire Rack can shave tires to match tread depth of existing tires if aren’t replacing all 4.

[Chicane_S54]

Originally Posted by Clifton

May be worth running the Transfer case calibration (VTG control unit) before buying new tires.

I’m running 275/40R20 (F) and 315/35R20 (R) and recalibrated shortly after replacing them 5k miles ago.

Worth noting, Tire Rack can shave tires to match tread depth of existing tires if aren’t replacing all 4.

Thanks. That hardly seems worth sending my existing tires to Tire Rack better to find a local tire place that can do the same.

[Clifton]

Originally Posted by Chicane_S54

Thanks. That hardly seems worth sending my existing tires to Tire Rack better to find a local tire place that can do the same.

Not sure that you read my post correctly. You mentioned buying new tires and looking at Tire Rack offerings. My post was intended to make you aware of that service if you were going to proceed with purchasing from them. Never implied mailing them back.

Good luck!

[crystalworks]

Originally Posted by Chicane_S54

BBS SX's with 275/40R20 Continentals

So that boils down to approximately 1/4" of wear. Could it be the 20" wheels are more sensitive to this difference in wear than the 19's? It looks as though I am looking at getting a new set of tires. What size tires are you running on your 20's.

Are your 20's staggered? When I go to Tire rack when I select tires by vehicle every 20" setup is a staggered setup.

I've got factory sized tires on staggered style 597 20's (275/40R20 (F) and 315/35R20 (R)) with Toyo Proxes STIII on them installed new in January I think it was.

I had a set of DWS' on them prior that had 30k miles+ on them when the tugging from the transfer case started. As soon as the Toyos went on the problem went away.

FWIW, I never had problems with tugging on the factory 19's and Bridgestone RFs. It could very well be possible that the 20's thinner sidewall wears the rears at a rate that makes the front to rear unhappy.

[Chicane_S54]

Originally Posted by crystalworks

I've got factory sized tires on staggered style 597 20's (275/40R20 (F) and 315/35R20 (R)) with Toyo Proxes STIII on them installed new in January I think it was.

I had a set of DWS' on them prior that had 30k miles+ on them when the tugging from the transfer case started. As soon as the Toyos went on the problem went away.

FWIW, I never had problems with tugging on the factory 19's and Bridgestone RFs. It could very well be possible that the 20's thinner sidewall wears the rears at a rate that makes the front to rear unhappy.

That is what I am thinking as well. The 20's seem to be a staggered setup I don't know if you can run 20's squared. What is the width of your rear wheels?

[crystalworks]

Originally Posted by Chicane_S54

That is what I am thinking as well. The 20's seem to be a staggered setup I don't know if you can run 20's squared. What is the width of your rear wheels?

20x10 F and 20x11 R, wheels were originally from an X6 F16.

In theory, you can run any wheel tire combo out there with a near identical diameter. Otherwise the 19's would have issues as they are not staggered.

I can see how this is frustrating. All things point to this being able to work without issue. Yet here you are. At this point... I'd try and service the transfer case fluid and run the calibration. Because why not. At any rate, I'm rooting for you.

[Chicane_S54]

Originally Posted by crystalworks

20x10 F and 20x11 R, wheels were originally from an X6 F16.

In theory, you can run any wheel tire combo out there with a near identical diameter. Otherwise the 19's would have issues as they are not staggered.

I can see how this is frustrating. All things point to this being able to work without issue. Yet here you are. At this point... I'd try and service the transfer case fluid and run the calibration. Because why not. At any rate, I'm rooting for you.

Will definitely do that this weekend. But I don't think anyone is running a 20" squared setup. These BBS SX's are 20 x 9, it may very well be that the drivetrain is too sensitive to run that squared setup. What fluid do you use for the transfer case?

[///d]

Originally Posted by Chicane_S54

That doesn't even make sense for 28 inch overall width on a 20" wheel/tire that would be .28 or approximately 1/4 of an inch diff. My OEMs are worn all to shit with at least that much diff and they give me zero drive-train issues.

Not to mention the vehicle hasn't kicked a single DSC or ABS code.

It doesnt matter if you have a 10" tall tire or a 100" tall tire, as long as all four tires are within 1% of eachother the electronics in the car "should" not care (other than your speedo being off). It is simply taking the rotational speed of each corner and comparing them. When one tire has a different overall diameter it will rotate a little slower or faster than the others. THAT is what causes the car to get upset and start triggering traction systems. The car does not know if you have 19's, 20's 22's, all it knows is the rotational speed at each corner.

It may not trigger any codes because it doesn't think there is anything wrong with the system, it just thinks there is wheel slip.

Originally Posted by Chicane_S54

BBS SX's with 275/40R20 Continentals

So that boils down to approximately 1/4" of wear. Could it be the 20" wheels are more sensitive to this difference in wear than the 19's? It looks as though I am looking at getting a new set of tires. What size tires are you running on your 20's.

Are your 20's staggered? When I go to Tire rack when I select tires by vehicle every 20" setup is a staggered setup.

Yes you can run 20's squared. I do and have for years with M Adaptive and DHP, always active, with no issues.

Some tire makes are spot on for their sizes, and some are not. I have seen a lot of people on these forums and in FB groups have issues with brand new conti's that are supposed to be the correct sizes to maintain that 1%. I have never ran conti's because of this.

An old room mate of mine used to manage a Discount Tire. He would often talk about how he could take two tires, same make model and size, and one would be taller than the other once mounted, even with the same lot numbers.

You can try the transfer case calibration and service, it may help, it may not. Won't know until you try.

[Chicane_S54]

Originally Posted by ///d

It doesnt matter if you have a 10" tall tire or a 100" tall tire, as long as all four tires are within 1% of eachother the electronics in the car "should" not care (other than your speedo being off). It is simply taking the rotational speed of each corner and comparing them. When one tire has a different overall diameter it will rotate a little slower or faster than the others. THAT is what causes the car to get upset and start triggering traction systems. The car does not know if you have 19's, 20's 22's, all it knows is the rotational speed at each corner.

It may not trigger any codes because it doesn't think there is anything wrong with the system, it just thinks there is wheel slip.



Yes you can run 20's squared. I do and have for years with M Adaptive and DHP, always active, with no issues.

Some tire makes are spot on for their sizes, and some are not. I have seen a lot of people on these forums and in FB groups have issues with brand new conti's that are supposed to be the correct sizes to maintain that 1%. I have never ran conti's because of this.

An old room mate of mine used to manage a Discount Tire. He would often talk about how he could take two tires, same make model and size, and one would be taller than the other once mounted, even with the same lot numbers.

You can try the transfer case calibration and service, it may help, it may not. Won't know until you try.

I will re-calibrate the TR but what it looks like is I need some new tires.

[///d]

Originally Posted by Chicane_S54

I will re-calibrate the TR but what it looks like is I need some new tires.

If the recalibrate doesn't work you may be able to work with the tire shop and work an exchange if you haven't put many miles on them, especially since you can show other setups do not cause issue.