[shark715]

Are they just for cosmetic purposes?

Do they change the handling of the car and/or tire wear?

Can they cause the wheel and/or axle bearings to fail early because the change in the geometry puts more stress on the bearings?

Thanks in advance for your help.

[bluemeanie]

Spacers will slightly increase the track width and therefore affect handling in theory. For example, more rear track width without an increase in front width would tend to decrease oversteer, making the rear end a bit less lively. This sort of thing can be fine tuned by using swaybar settings if necessary. Another reason for spacers is to provide additional clearance between wheel/tires and suspension components.

There should be no problems with increased tire wear or premature bearing failure.

[Cyberdemon]

Generally yes they are purely cosmetic - I don't think anyone would be able to seriously quantify the handling benefits of an additional ~1" of overall track width on handling.

The handling and tire wear changes are also minimal - it is similar in effect to buying an aftermarket wheel with a different offset. Compared to suspension modifications which change the geometry and handling characteristics more dramatically.

As far a failures - it could cause your wheel bearings to fail earlier than normal, but again it's no different than if you got a set of aftermarket wheels with a different offset. As long as your wheels are properly torqued and the spacers are hub centric so they properly distribute the load I would no be worried unless you're planning on keeping the car for 200k miles.

[Transfer]

They're cosmetic. Anyone saying they improve handling is just trying to justify their waste of money. In fact, in theory they actually wear your wheel bearings faster, but I doubt it is significant.

I've used spacers on multiple cars (including my M235i), but I regret it every time I need to take them off for winter wheel swaps. They can be a massive PITA to get off some times, requiring a torch, hammer, prying... ugh I hate them so much... and yet I still use them because OEM wheel offsets are always terribly conservative.

[Merc for hire]

Wheel spacers are sometimes necessary for our cars because our brake calipers are so thick. Most wheels from past BMW don't clear it.