[Save Bluth]

I just had KWv3s installed and at the same time put on a different set of wheels I bought that came with tires (189s with Mich Pilot Sport A/S). When I got the car back, the drop was LOW. Looks very cool, but I'm a bit concerned with it being too low. Also, ride is much more firm/stiff than I wanted. Both of these issues will hopefully be resolved today as I'm going back to the shop for adjustments.

Here's the real issue: I've noticed that in a variety of conditions, I get a warning indicator about DSC/DTC (the flashing triangle and circle arrow). This indicates that one or the other driver aid is controlling the drive. And, I definitely feel it. If I let off the accelerator, the warning lamp goes out and things are fine. Unfortunately, this happens a lot for example: under hard acceleration, going over a reasonable bump while at speed, in wet conditions, etc.

One last piece of info: The tires I got with my wheels are 255/40/18 in the rear. The stock size should be 35 series, so mine are definitely "taller".

Is this tire size variance the most likely culprit? Or, is it more likely to be the stiff suspension that's allowing the tires to lose adhesion? Finally, am I putting significant stress on any other parts (diff)? Thanks.

[GregL]

Bingo, you're right about the tire height, they're too tall. You could have gotten away with 235/40/18 but 255/40/18 is a whole inch off from factory spec and although xDrive is much more forgiving than Subaru's AWD for example, it seems that you've struck the borderline between ok and not ok.

[NM_BMW]

What size are in the front?

[Save Bluth]

Fronts 235/40/18
Rears 255/40/18

If I compare the fronts to rear, as is, the difference between them is .6 inches (or 2.42%).

If I compare the current rear to the stock rear (255/35), the difference is 1.006 inches (or 3.8%)!

I am clearly going in the wrong direction. I have to believe this is the problem. About to pick up my car following suspension adjustment (going a bit softer). If problem remains - it's the tires.

Assuming this is the case, I'll now have to decided whether to go staggered (225/40 and 255/35) or non-staggered (probably 235/40 all the way around).

Thoughts?

[40yroldawakening]

On an AWD car, you can not run different sizes frt & rr. You have to stay with the same size all around. I would get this taken care of soon, I wouldn't even drive any until you do. The dealer may also void your drivetrain warranty.

[NM_BMW]

Originally Posted by 40yroldawakening

On an AWD car, you can not run different sizes frt & rr. You have to stay with the same size all around. I would get this taken care of soon, I wouldn't even drive any until you do. The dealer may also void your drivetrain warranty.

This is false.

You can run staggered on a AWD. You just have to make sure the rolling diameter has a difference less then 1%. BMW would not sell staggered setups with the XI if it couldn't run staggered.

The popular setups are:

235/35/19
265/30/19

or

235/35/19
275/30/19

Not all brand of tires have the same rolling diameter even if the size is the same.

[Save Bluth]

Well, I've seen the various discussions on whether the XI can run with staggered and I think I'm ok there. My problem really is the variance in diameter. I will be getting this fixed (new tires!) and praying that damage has not already been done.

If this is crazy, just let me know: I'm thinking of slightly adjusting air pressures (a bit lower in rear, a bit higher in front) to temporarily and partially make up the difference in diameter. I'm not sure if this adjustment would affect street tires. But, I know that adjusting pressures and the resulting impact on tire "size" is considered in some racing applications. Anyway, not a solution - just a band-aid.

[Ferg]

I have a staggered set up with 18s for my winter set up and 20s on for my summer. No problem with them even lowered on KW V3s. I agree with you on the stiffness of the ride. It it didn't handle like it was riding on rails, I'd almost change back to OE suspension.

[Kev]

Originally Posted by Ferg

I have a staggered set up with 18s for my winter set up and 20s on for my summer. No problem with them even lowered on KW V3s. I agree with you on the stiffness of the ride. It it didn't handle like it was riding on rails, I'd almost change back to OE suspension.

I don't feel any stiffness with my KW V3. The handling is vastly improved. I just don't like how the coils stack on top of each in the front.

[halB]

Originally Posted by Humtek

This is false.

You can run staggered on a AWD. You just have to make sure the rolling diameter has a difference less then 1%. BMW would not sell staggered setups with the XI if it couldn't run staggered.

The popular setups are:

235/35/19
265/35/19

or

235/35/19
275/30/19

Not all brand of tires have the same rolling diameter even if the size is the same.

235/35-19 F 265/35-19 R IS NOT OK FOR Xi! F/R speed difference is 3.2%. You will definitely kill your transfer case clutch pack.

Even 235/35-19 F 265/30-19 R is not the best. F/R speed difference is -0.8% (rear tire being smaller). Too close to the 1% limit for comfort.

If you have to have 19" staggered in an Xi, you should go 235/35-19 F 275/30-19 R. Speed difference is 0.1%. Just make sure you have the correct offsets so nothing will rub.

FYI - The factory set-up of 225/40-18 F 255/35-18 R has a speed difference of -0.2%.

For the OP - Don't drive your car until the tire size issue has been resolved. With 2.5% speed diference in your setup according to my calculation, you are playing with fire. If you smell smoke, it will be your clutch pack burning!! (You won't exactly smell smoke but you know what I mean.)

[Kev]

Originally Posted by halB

235/35-19 F 265/35-19 R IS NOT OK FOR Xi! F/R speed difference is 3.2%. You will definitely kill your transfer case clutch pack.

Even 235/35-19 F 265/30-19 R is not the best. F/R speed difference is -0.8% (rear tire being smaller). Too close to the 1% limit for comfort.

If you have to have 19" staggered in an Xi, you should go 235/35-19 F 275/30-19 R. Speed difference is 0.1%. Just make sure you have the correct offsets so nothing will rub.

FYI - The factory set-up of 225/40-18 F 255/35-18 R has a speed difference of -0.2%.

For the OP - Don't drive your car until the tire size issue has been resolved. With 2.5% speed diference in your setup according to my calculation, you are playing with fire. If you smell smoke, it will be your clutch pack burning!! (You won't exactly smell smoke but you know what I mean.)

LOL~

Do you know that not all tires are created equal? You can run your calculations all day long to find a set that has 0.00001% difference, but at the end of the day, depending on what kind of setup you have for tires, the percentage will change. A set of 235/35R19 front / 265/30R19 rear Michelin PS2 is different from a set of Bridgestone RE050A PP in the same size. You have to look at the number of revolutions per mile to find out the closest match possible.

[halB]

Originally Posted by Kev

LOL~

Do you know that not all tires are created equal? You can run your calculations all day long to find a set that has 0.00001% difference, but at the end of the day, depending on what kind of setup you have for tires, the percentage will change. A set of 235/35R19 front / 265/30R19 rear Michelin PS2 is different from a set of Bridgestone RE050A PP in the same size. You have to look at the number of revolutions per mile to find out the closest match possible.

Please see my latest posting http://www.e90post.com/forums/showthread.php?t=186216

[NM_BMW]

Originally Posted by halB

235/35-19 F 265/35-19 R IS NOT OK FOR Xi!

My fault I was typing to fast. It is

235/35/19
265/30/19

i edited my post.

Most shops have the exact rolling diameters for each make of tire. This is best to use compared to the tire calculator that is on the boards. I had my shop do my FK452's in 235/35/19 Front and 275/30/19 Rear and they have the exact same rolling diameter.

[Mau1976]

I am running 235/35/19 Front, and 275/30/19 Rear on my 2006 330xi, Can I use the KWv3s? I would like to lower my car, but I don't know if it would be ok. If it is possible, how much (approximately) would it cost for the installation? and how long does it take to install the product?

[Kev]

Originally Posted by Mau1976

I am running 235/35/19 Front, and 275/30/19 Rear on my 2006 330xi, Can I use the KWv3s? I would like to lower my car, but I don't know if it would be ok. If it is possible, how much (approximately) would it cost for the installation? and how long does it take to install the product?

Hi~

I'm a fellow badger. I just had my KWV3 installed this week. as long as you have correct offset of wheels (~ET30 in the back for a 19X9.5 wheel), you should be fine with a drop. I was able to drop it about 1.25" both front and back and my rear wheels will rub occasionally (mine's a E92 and the back wheel si 19X9.5 ET27).

If you want quality work done on your car, I would recommend Kelly Moss off of Badger Road in the south side of Madison. They are Porsche experts but also work on Mercedes, BMWs, Audis and VWs.

[Mau1976]

I think that my rear wheels are 19X10 but I am not completely sure. When I ordered them they told me they were 19X9.5, but I think that the box said 19X10 (I can remember). Do you think that, it would make any difference? How much did you pay? Thank you for oyur help.

[Kev]

It would make a difference. There's a calculator in the Tire / Wheels section that allows you to calculate the difference in offset of your wheels. Try to find out what size your rear wheels are and what the offset is.

I paid quite a bit more than most people around here for the coilover install but it's done by a BMW race specialist with proper alignment and suspension setup, so in my mind is well worth it.

[Nikolas]

I think the best calculator out there is this one.

http://www.miata.net/garage/tirecalc.html


I run 235/35/19 fr and 275/30/19 rear

[e90fanatic]

does anybody know if Micheline Pilot Sport A/S Plus (235/40/18) all around fit the sport pkg wheels?

[GregL]

Originally Posted by e90fanatic

does anybody know if Micheline Pilot Sport A/S Plus (235/40/18) all around fit the sport pkg wheels?

Definitely, they support a rim between 8-9.5". Infact I'm running a set of Goodyear Eagle F1 All-Season 235/35/19 on my summer set which are staggered 8.5F, 9.5R and they look and drive perfectly fine. If anyone tells you that it's a stretch to put a 235 on a 9-9.5" rear wheel I'd argue that it's not. Tire manufacturers for safety and liability purposes wouldn't allow it if they thought for a second that something may go wrong. I have a photo that I took earlier this year if you want to see how a 235 tire sits on a 9.5" wide rim.

[e90fanatic]

Originally Posted by GregL

Definitely, they support a rim between 8-9.5". Infact I'm running a set of Goodyear Eagle F1 All-Season 235/35/19 on my summer set which are staggered 8.5F, 9.5R and they look and drive perfectly fine. If anyone tells you that it's a stretch to put a 235 on a 9-9.5" rear wheel I'd argue that it's not. Tire manufacturers for safety and liability purposes wouldn't allow it if they thought for a second that something may go wrong. I have a photo that I took earlier this year if you want to see how a 235 tire sits on a 9.5" wide rim.

thanks. how about the fronts? stock size is 225/40/18 vs the tire i want to put on 235/40/18...will that be a problem?

the reason is that I just want a set of tires to run on (even if all 4 tires are exact same size) and Michelin Pilot Sport A/S Plus in 255/35/18($379) are extremely expensive relative to 235/40/18 ($218).

[GregL]

Originally Posted by e90fanatic

thanks. how about the fronts? stock size is 225/40/18 vs the tire i want to put on 235/40/18...will that be a problem?

the reason is that I just want a set of tires to run on (even if all 4 tires are exact same size) and Michelin Pilot Sport A/S Plus in 255/35/18($379) are extremely expensive relative to 235/40/18 ($218).

Not a problem. It's quite common to put 235s on the front of an E9x while maintaining the same profile.

FYI Here's how my non-staggered tires look on my staggered wheels:

Edit: Goodyear builds in a VERY generous rim protector as you can see. However I've seen a number of other tire makes where the metal of the rear lip would be sticking out. Just keep it in mind.