The rubber seals on the RV-12 main wheels are indeed lip seals. They are removable and not integral with the bearing.
Tapered roller bearings are excellent for radial and axial loads. Also, very good at absorbing static loads such as hard landing. Tapered rollers have large surface area in contact bearing race to distribute force. These bearings do not have integral seals and required either removable lip seal or dust cup like on front wheel of automobile. Tapered roller bearings consist of two separate pieces – inner race with roller/cage and separate outer race.
Ball bearings have point contact between balls and bearing race which is poor for absorbing static loads. Some ball bearings are designed for combined radial and axial loads but don’t approach robust design of tapered roller. Ball bearings can have integral shield or seal. This is possible because the bearing is assembled as a single unit with inner/outer races and ball/cage.
Jim Stricker - EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 670
LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H