I want to get carbon rims for my wife’s fat bike Farley 9.6.  The wheels on there now are 27.5 x 80 mm   If I buy 27.5 x 68 mm rims can I put 4.5 inch tires on those?   Ideally I would like to just pull the tires off the steel rooms, and go tubeless. Peter Xu has those rims.  The rear derailleur is SRAM GX.  Does anyone see any problem with switching to these ?

Rode 10 miles on Snowmobile trails yesterday . components worked great . After Ride had to re tighten headset and am trying to figure out "creaking" sound in BB or crank( goes away when stop pedaling or when pedal hard) doesn't appear to be any play in spindle ?? 

Things learned :
Frame is well thought out.Hydraulic line to rear brake  runs easily thru the frame with no trimming . Rear derailleur cable runs down inside  frame , then outside frame under BB and back in chain-stay to exit by derailleur.
Front fork with integrated crown race appears to be working well. ( time will tell) I used headset from Carbonspeed. If it loosens routinely, i may have to try another. Front hub has 2 caps that adapt to fork, they are loose and have to be careful when removing wheel as could easily lose them . They are supposed to have a ring washer to help hold them in place, mine dont . Peter ??

i mounted surly bud and Lou tires , have great clearance with frame and chain, (Raceface for 190 rear spindle ). I dont think snowshoe 2XLs would clear frame for anyone out there thinking of that.

Wheels went tubeless without a hitch using gorilla tape. I bought latex strips from Fattystripper.com ( firewall at work wont let me go to that website  )after watching his video and will mount them later.
My final weight came  in at 27 lbs including platform pedals (Chromag contact ).
still cant post picture cause "upload folder is full " at this website.

In looking at my headset , peter Xu tells me that my carbon fork has an integrated crown race such that the carbon fork sits right against the bearing. The "integrated crown race " seems a little rough ,
Does anyone have any experience with this or suggestions ??

Almost everything is ordered. Nothing has arrived
19" CS-N019 frame
Carbon fork
Wheels : 100 mm NSS-FHR 100C , 150x15 through axle front,197x12 rear with XX1 driver hub
FSA headset
B8 riser handlebars 720 mm
ST2 stem 80mm
SP7 seat post no setback , clamp
RaceFace Next SL crank for 190 mm rear, direct mount chainring 28 teeth, crank boots,BSA 100mm bottom bracket
SRAM XG-1199 cassette,XX1 derailleur,pc XX1 chain,XX1 trigger shifter
Shimano XTR M9020 trail brakes, SM RT 86 160 mm rotors

Haven't ordered Surly Bud/Lou tires, pedals , valves
SRAM

i just found this forum, have been browsing on MBTR.
I ordered this week from peter at Carbonspeed:

19 " CS-N019 frame
Carbon Fork
Headset,Stem,Handlebars,Seatpost
100 mm Wheels with SRAM Hub

now have to get components:
planning on XX1 1x11 Deraileur
need to figure out crank ( brand and spindle length)and Bottom Bracket , Chain Ring 28,30,32 ?brand , flipped ?

I am looking for any advice on any and all parts.
Brakes Shimano or Sram ?
Tubeless tires

I have never built a bike but hope to  find local help ( Syracuse anyone )

Thanks in advance