[Nattha]

So I have this G31 530i xdrive 2017 model with M-sport brakes package (S2NH). I want to upgrade my brakes to something better, since they are warped and needs to be changed. Unfortunately I did not do so much research... So I bought Zimmermanns rotors and pads.

New rotors: 395mm front and 370mm rear.
Wheel setup: 20" Summer wheels and 18" winter wheels
Questions:
Do I need bigger calipers? M-performance "red" calipers or will these rotors fit M-sport blue calipers.
I guess 18" wheels might be a little too small for these rotors, but just to make sure. Does it fit?
If I want to keep the 18" wheels and calipers, what is the biggest rotors size I could use?

Thanks in advance, come with any suggestions and solutions!

[Chappers 71]

No you just need the larger caliper carriers. The front & rear M Sport & M Performance calipers are the same

If you wanna keep 18” wheels then you’ll need the 374mm & 345mm discs.

I recently fitted a set of Zimmerman cross drilled discs & they are very good

[Nattha]

Originally Posted by Chappers 71

No you just need the larger caliper carriers. The front & rear M Sport & M Performance calipers are the same

If you wanna keep 18” wheels then you’ll need the 374mm & 345mm discs.

I recently fitted a set of Zimmerman cross drilled discs & they are very good

If I change to 374mm and 345 discs, do I still need larger caliper carriers?
Do you also have link for larger carrier?

[Chappers 71]

If you have the M Sport brakes then you already have 374mm front & 345mm rear discs, just do a little research

No I don’t….you want me to fit them for you as well

[Nattha]

Originally Posted by Chappers 71

If you have the M Sport brakes then you already have 374mm front & 345mm rear discs, just do a little research

No I don’t….you want me to fit them for you as well

I'm asking because it is easier to get answers from someone who might have done the same, if you don't like to answer questions then don't bother to answer.
But yea feel free to put them on for me, mister with knowledge but dont like to share.

[Chappers 71]

Well had you done a little research first you’d have not bought the wrong size discs.

Yes it is easier to ask here & I told you that you only need the larger caliper carriers…I had also posted a screen shot of the 374 & 345mm discs I had fitted to my G31….so why would I have the part numbers for the larger caliper carriers?

[Nattha]

Originally Posted by Chappers 71

Well had you done a little research first you’d have not bought the wrong size discs.

Yes it is easier to ask here & I told you that you only need the larger caliper carriers…I had also posted a screen shot of the 374 & 345mm discs I had fitted to my G31….so why would I have the part numbers for the larger caliper carriers?

Well I have connected the dots while looking at other posts, I actually don't have 374 and 345mm, but 348 and 345mm it is the 530 and not the 540.

[Chappers 71]

So you don’t have option S2NH then? Do you have blue calipers?

[Nattha]

Originally Posted by Chappers 71

So you don’t have option S2NH then? Do you have blue calipers?

According to Mdecoder I have S2NH and yes I have blue calipers. I saw another post where one mentioned different rotor size based on engine. According to him 530i M-sport rotors are 348 and 345 which seems correct due to I am not able to purchase 374 and 345 through Autodoc when selecting my car.

[TEF]

It appears that the Major General, in this case, has taken a rather strident positon towards, to what appears to be, a simple question about rotor sizes from a New Member. There doesn't seem to be any request from the New Member that the Major General "fit them" for him. Not clear how the Major General's "assistance" will attract more New Members to the fourm.

[Chappers 71]

Nattha If the 348 & 374 brakes share the same caliper carrier then the 374 should fit if not then same as with the 390mm you’ll need to change the carriers & most likely the brake backing plates. Check the part numbers for yours & a 540i, use real oem. Or you could stick with the 348 & go cross drilled/dimpled or slotted discs with ceramic pads

I am surprised that you have the smaller discs with the m sport brakes, even if it’s a 530 as the bumpf for option S2NH says larger discs…every day is a school day

[Chappers 71]

Originally Posted by TEF

It appears that the Major General, in this case, has taken a rather strident positon towards, to what appears to be, a simple question about rotor sizes from a New Member. There doesn't seem to be any request from the New Member that the Major General "fit them" for him. Not clear how the Major General's "assistance" will attract more New Members to the fourm.

Yeah maybe I was a little harsh…but a bit of research is key & I have now learned that not all G30 m sport brakes have 374mm front discs

[TEF]

Assuming one has Brembo-style front calipers (no matter the color), the rotor size is clearly cast on the caliper's backside. While I am no expert, it seems that BMW paints these Brembo calipers in a variety of colors including raw aluminum depending on the vehicle, so these casting marks are the surest way to determine rotor and pad sizes.