# BBS GT4 RE Installation Day
Today is GT4 install day! After finally caving and buying tires on Tuesday, it's time to install them!
## Goal for Today- Install Apex 90mm wheel studs
- Install Apex 15/18mm Spacers
- Install BBS GT4 REs w/ 275/35/18 Michelin PS4S
- Remove TPMS (Tire Pressure Sensor) or referred as RDC
- Code in FTM (Flat Tire Monitor) or referred as RPA
## Coding
The BBS GT4s use 8mm valve-stems instead of the factory BMW 11mm valve-stems. For those who wish to retain TPMS sensors, there is an option here:
https://**************/BBS_wheel_TPM...4_p/bbsrdv.htm I personally didn't want to spend the extra money for this and second set of sensors. I figured the economical decision is to ditch the whole wheel sensors altogether and revert back to the Euro E9x/Pre-LCI E9x FTM system.
FTM = It uses the speed sensors in each wheel and compares rotational speeds to check if there is a differential between wheels. This will determine if there is a flat if there is a large deviation. The con is if there is a decrease in tire pressure across ALL tires due to not checking, it will not detect that. (ie. All tires drop to 29psi instead of set 33psi)
TPMS = This uses sensors in the wheels and connects to a main RDC unit in the passenger rear wheel well (at least for LCI E90 2010+). This system is more accurate but can get costly with extra sensors when multiple sets of rims or in my case, racing rims that were not designed for TPMS.
During my research, I found a thread that describing exactly what I wanted to do!
http://e84.xbimmers.com/forums/showthread.php?t=1145078 Thanks
improvius for documenting this awesome finding!
The first step is to take off the rear right wheel and undo the inner fender liner. After that, I unplugged the RDC module which is in the lowest rearmost area of the fender liner. Next up, coding!
### NCSExpert changes- Remove $2VB vehicle order
- Add $265 vehicle order
- FA Write to the CAS module
- Either code defaults to CAS, KOMBI, DSC, CIC or add the following code to the corresponding module:
Code:
CIC: RPA_CIC
aktiv
CIC: RDC
nicht_aktiv
CIC: RDC_SAFETY
nicht_aktiv
KOMBI: RDC_ALIVE
nicht_aktiv
KOMBI: MMI_ENA_RPA_RDC
aktiv
KOMBI: RDC_VERBAUT
nicht_aktiv
KOMBI: DSC_MIT_RPA_CC
aktiv
KOMBI: RDC_DISP_SWITCH
nicht_aktiv
MK60_M3: RPA
aktiv
CIC module now shows FTM instead of TPMS!
## Installation
A small storm as passed through San Francisco and today had a slight 50% chance of rain mid-day. Luckily the driveway wasn't too bad.
Off comes the 219M wheels! The PSS tires only have about 3k miles on them so they are looking sharp!
My cousin's 328i E90 in the background just happens to be on GT4s too
My brother's Msport 11 E90 335d, Cousin's 08 328i and my 11 E90 M3.
Installed!
After I reset and initialized the FTM, I drove around it now shows active instead of FTM malfunction!
Few more pics:
## Impressions
Final Specs:
- Front: 18x10+25 275/35/18 Michelin PS4S
- Rear: 18x10+22 275/35/18 Michelin PS4S
The rear looks like it has room for a 20mm spacer instead of an 18mm. The front is perfect with the 15mm spacer. For now, I'll leave it as is. I didn't get to drive it more as I had some errands to take care of. Back into the garage, it goes!
Initial impression of the square setup is that the steering is a bit looser but I will check more the next time I drive it. I'm now itching to lower it... YIKES.
Thanks for reading!
