[MPR 151]

I have a 2018 340i Base model (non painted calipers) and I'm ready to do the brakes but when buying I realized I don't know if I have 340 or 370mm rotors, or if that even matters.

So how can I tell which size I have, and if I have the 340's can I get the 370'S?

I'd like to get the Power Stop Z26 Street Warrior 370mm

https://www.rockauto.com/en/moreinfo...40232&pt=13824

But need to answer this 340 vs 370 questions first.


Also, I'm open to recommendations of other brake sets in the $250-$300 range

[sqwinny]

Non painted is 340mm. You need painted calipers that say 370/380 on the back. You'll see it on the right side. You should have 340 stamped there.

https://i.ebayimg.com/images/g/TggAA...hd/s-l1600.jpg

[MPR 151]

Originally Posted by sqwinny

Non painted is 340mm. You need painted calipers that say 370/380 on the back. You'll see it on the right side. You should have 340 stamped there.

https://i.ebayimg.com/images/g/TggAA...hd/s-l1600.jpg

Thanks for the info. Also I'm assuming if I have 340, then I gotta stick to 340?

That seems obvious but I want to confirm first.

[Billfitz]

340mm is 13 3/8 inches. 370mm is 14 1/2 inches. For a daily driver plain works better than slotted and drilled, which may look nice but only work better when tracking. Evolution coated is worth paying for.

[johnung]

Originally Posted by MPR 151

Thanks for the info. Also I'm assuming if I have 340, then I gotta stick to 340?

That seems obvious but I want to confirm first.

Grey calipers on a 340i means that you have Front 340mm x 30mm and rear 330mm x 20mm. Rotor size is specific to calipers. So you can only change rotor size if you change calipers.

Used pair of 370 calipers are about $550-$650 and then you need 379x30 rotors. Pads for 340 and 370 are actually identical.

Zimmermann makes excellent German replacement rotors. FCP Euro has them. If you want an upgrade get StopTech full crossdrilled rotors. Crossdrilled are best for street which is why BMW installs them on M3/M4. Great bite and great in the rain. See photo

Hawk 5.0 pads are best for street. Great bite, instant warm up and light dust. See photo