wheel spacers and bearings

a question recently came up on another board to which i have not found a satisfactory answer.

do wheel spacers put undue stress on the wheel bearings? are they suitable for a daily driver?

i've seen plenty of responses on several boards citing mostly anecdotal "evidence" (term used loosely), but no REAL facts to back it up. can anyone shed a little more light? thanks.

Wheel spacers do not put excess stress on the bearings. Yes, the extra space gives the wheel more leverage to place stress on the bearings over bumps etc, but the bearings can handle it easily, as they are designed to cope with vehicle weight, hard cornering etc.
Spacers DO increase loads and stress on wheel studs, and effectively makes them weaker. This is the hazard. The spacer moves the center of shearing force Where the lug nut sits further away from the anchoring point (hub)
Some older aluminum wheels (Cragars) were designed with reinforced lug nuts with threaded collars on them to reinforce the studs, to fight this problem.
Personally, I would not use any spacers on my cars. I would get wheels with the correct offset.

Gotta throw in my $.02

It depends on if the tire is going to be in the same position as before spacers. When the bearing carriers were engineered, they had already accounted for where the tire will be and how much vertical and axial loads will be transfered to the bearing. If you move the tire, you're moving the load points of the bearings causing it to take on more axial load.

Think of it in an extreem case. If you put 2 foot spacers on your wheels, the bearings are going to have almost no vertical load but all axial load.

Does that help?

Gotta throw in my $.02

It depends on if the tire is going to be in the same position as before spacers. When the bearing carriers were engineered, they had already accounted for where the tire will be and how much vertical and axial loads will be transfered to the bearing. If you move the tire, you're moving the load points of the bearings causing it to take on more axial load.

Think of it in an extreem case. If you put 2 foot spacers on your wheels, the bearings are going to have almost no vertical load but all axial load.

Does that help?
You are correct, but as spacers are quite small, the increased load on bearings is usually within their deslgn limits.
You are on to something else, though,
Adding spacers changes the effective offset of the rim and will affect handling.
However, if you have non stock rims with more offset, you can use spacers to bring the effective offset to stock and restore handling.