I have a set of 17x7.5 42mm offset wheels. Will 12mm spacers give me any rub issues? I have aftermarket springs, lowered at Front: -1.22"
Rear: -1.1". Im pretty sure it will rub but i dunno. Also are there any 8mm hubcentric spacers on the market?

 

Have you used your 17x7.5 wheels with 205/45-17 tires on your lowered MINI already? No rubbing right?

So why are you trying to add spacers? To make it look more aggressive, for a wider track?

There is no performance benefit to adding spacers for street use. You should think of the spacers as for cosmetic appearance or for clearance if you are rubbing on suspension parts.

The way you are right now is fine as the 17x7.5 wheel with +42 offset is roughly the same fitment as stock 17x7 wheels with +48mm offset. Since you have stock sized tires you are fine given you are lowered quite a bit- much more lowered would likely reduce performance not improve it.

If you look at your rear tire upper tread edge, how much clearance or gap do you have before it hits the lower inner wheel arch plastic? This gap limits the amount of spacer you can use.

If you use 12mm spacers I think you will be likely to rub front and rear depending on how much front and rear negative camber you are running. If you have adjustable front camber plates you can make the front as negative as possible to increase clearance. But in the back you don't want the camber to exceed about -1.8 degrees since it will increase oversteer if you overdo it. Mostly you can use negative camber to help angle the tire a bit to aid clearance. Your suspension drop is extreme so you don't have much clearance. A 12 mm spacer moves the wheel 18mm or 0.7" more to the outer side- think of the wheel and tire sitting 18mm outward.

What makes more sense is to use a small spacer about 5mm. This would move the wheel 11mm or 0.4" outward. See if that might work, it's less extreme.

For spacers-
http://www.outmotoring.com/mini-coop...el_spacer.html
http://www.altaperformance.com/p/232
http://www.andysautosport.com/mini/2...l_spacers/h&r/
http://www.andysautosport.com/mini/2...pacers/eibach/



Take a look at this diagram-


HOW TO MEASURE

Place a straight edge flush with the face of the wheel and tire combination. Make sure the straight edge touches the tire in two spots to keep the straight edge even with the tire. Measure from the inside of the straight edge to the inner fender lip. (see diagram) Take the measurement at the point where the wheel and tire is closest to the fender. For instance, on a car with a large amount of negative camber the tire and wheel may be closest at the front or rear edge of the fender.

 

Man, thank you for the in depth reply its very much appreciated! Its strictly for cosmetic reasons, i ran my 12mm's on my stock 16" cooper wheels and im very aware of what spacers do such as bearing wear and stability. I dont track my mini and dont plan on it, its my daily driver and im pretty much going for a clean, symmetrical look. The wheels i have on it now dont really compliment the stance that much. To my liking anyway, my question is just what im asking, my only concern is harsh rubbing and clearance. I have seen similar sized wheels with 8mm spacers that give the aggressive look i want but im oly asking if 12mm's would be ok because i already own them.

 

If you already have the 12mm spacers and wheels and tires then try them on and see if they rub once the wheels are mounted- you can do it yourself if you have a socket wrench and jack. If you don't find a MINI owner that does and you can change out your wheels and add the spacers to see if you have enough clearance. Odds are you do not.