Cheap Wheel Spacers

i got them front and rear but the ones in the front are different they just screw one the stud with piece goin all the way around i got them off ebay and havent had a problem yet the ones in the rear are polyurathane and ive had them for like 3 years now and they still look brand new
 
Polyurathane wheel spacers? Are they the ring type? Sounds like it wouldn't be strong enough for an application like this. Tell me more about them, please?
 
I do the front wheel flip and I"m purchasing some rear solid spacers from a guy on here. Yeah, moving the centerline of the wheel out further will wear out the bearings more quickly, but it will also add stability!! Wheel bearings are like 20 bux for a set with the seals....I'd say it's worth doing the bearings more frequently. Keep in mind most performance mods you do are decreasing the life of the motor or other parts anyways. If longevity of the vehicle was the main goal, then everyone would be riding stock vehicles!! Fun has it's price you know!