Time Slips & Disk Breaks (i guess)

well right now im 4 " BP all the way around.. Mini tub in the rear is a few years off.. so i was planning on going on a split set. upgrade to a 4.5 in the front via the disk brake change and keep the 4.0 bp in the rear untill the upgrade.

my understanding is wheel options are just alot more plentiful for the bigger pattern.