I'm not going to get into the whole bearing stress issue. A differing back spaced wheel with equal distance to a spacer use will have no more leverage on the bearings comparing between each other. In other words they're both adding more leverage.
There are spacers that are just plates using only the hubs studs to hold it. Whatever that spacer thickness is takes that much distance away from the distance the wheel is fastened by said stud.
Then there are the bolt in spacers with new studs. While these have a new set of five studs you're now doubling up the lugnuts for each wheel by needing to torque down the spacer bolts first, then torque down the wheel lugs to the spacer.
As a certified state inspector in Pennsylvania I can tell you they're illegal. Period. Im not sure wgat the yahoo was thinking making them illegal in my state but my personal thoughts are this.....................
I don't care if you hurt yourself but hurting other innocent motorists and or bystanders is wrong. Really wrong. I know people have run spacers for a long time with no issues but the fact still remains you're adding a component that could pose a danger. Inferior material could be a cause but the biggest of all is human error. Setting a spacer and forgetting about it happens much more than people checking them routinely.
Moreover IMO adding a component to a high stress area is a bad idea.
Stacking blocks on the rear of a truck under leaf springs...people get away with it most times but a block can kick out from under. A single block is legal in the rear but the rear has mostly a vertical stress.
You can get some torque twist and there is the iffy situation. You stack blocks and now it gets even more hairy.
The front should never get a block under a leaf because we still have the vertical stress but have added a great degree of lateral/horizontal stress by this being a steered axle.
Do you stack blocks under a body to get a desired lift height or just one block of proper length?
Would you weld two coil pieces together to get a desired coil height? A good weld is stronger than the steel itself.
Bad idea. Adding another component is making a daisy chain of things and the more you add bad odds increase.
Technically I'm supposed to fail a vehicle with front side tinted windows. Do I let some go. Maybe
...but Tinted glass has no impact on the other innocent motorists. Zero!
Human error...
We've seen many rigs come in with spacers for inspection or other repairs and it's really astounding how much neglect goes on. Many have a stud missing or broken on the spacer side of things holding it to the hub. How could that be? Well they couldn't see it.
Fucking incredible really...that things like this get ignored yet we see them way too much. Spacers not torqued down to proper specs any longer. Perhaps they never were to begin with.
The biggest thing that annoys me is people want to modify their rigs and have such little care about safety of others. They are in such a frenzy to modify the rig and are looking for the cheapest way possible. Everything is dollars driven instead of function, fit and most importantly safety.
I'm not saying everyone is a cheap skate as some might be trying to keep a certain wheel that was never offered with a certain BS.....
....but again IMO you're altering a vehicle from OEM which brings a need to move your stance outward. You got a bigger tire and now rub....but you just loooovvveee those factory wheels. No damn factory wheel is worth a loss of safety by having to add a spacer. Maybe you consistently check your spacers abd the condition there of. What about the next person you sell your rig too? What about the person that asks how you got those wheels to sit like that. Spacers. You can go into the big speech of always monitoring them but will they? I can promise you at least half won't. More people than you can imagine get in these machines and just drive with absolutely no sense of feel to what their vehicle is doing.
There's a reason we put a god damn next oil change sticker on their windshield.
Modifying costs money. Modifying properly and safely costs even more money. It's the game we play but to play it right you need to pay.
Get some wheels with proper BS instead of creating a damn daisy chain.
Sorry for the long response but I felt the need to vent on this and worked at it off and on this morning.
Good day