What is the difference between bearings with 2z and 2rs sealing?
A 2rs type seal has two rubber lip seals rubbing on the inner ring, which allows it to prevent the intrusion of water or other fluids harmful to the proper functioning of the bearing.
Equivalent suffixes for these bearings are type: 2RS, 2RSH, 2RS1, 2RSR, LLU, DDU EE
A 2z type seal has two metal flanges or deflectors which prevent the intrusion of dust, there is a clearance between the deflector and the inner ring, so water can get in!
The suffixes used are ZZ or 2Z
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2rs sealed bearings
2z sealed bearing
ZZ have a steel shield protecting the cage and balls from large objects. Liquids and fine dust easily get in.
RS is a contact rubber seal. It will keep everything out in normal use. If there's a pressure differential across the bearing then the grease does get forced out the low pressure side but that would be a misuse of the bearing. The seal is not sufficient for underwater use.
I would use 2RS on wheels and not remove the inner seal. The bearing will retain its grease and run smoothly for many years.
The seal does have some friction, for wheel application this is trivial. You will notice it trying to do a static balance on a wheel but a good balancing stand has its own low-friction bearings.
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