I'm assuming you're speaking of a bearing kit like # BK3-310 that includes a LM67048 outer bearing, a 25580 inner bearing and a GS-2125DL double lip seal. The seal fits a 3.376 hub bore and a spindle surface just a bit larger than 2.125 inches.
The grease seal should fit very tightly in the hub bore and should not be loose. If it fits loosely on the spindle or in the hub bore, it will allow grease to escape the hub and allow moisture and dirt in.
If you would reply with the inner bearing,... view full answer...