I lowered my car on my stock wheels. I was looking online for spacers and found a set of 12mm universal 5 lug spacers for $12 on ebay. Will these work fine?

 

12mm = almost 1/2"

For 12 bucks? Are they made of plastic? For that price I think you might risk your wheels falling off.

 

I wouldn't do it. Years back, I got universal spacers as a temporary fix. I bought new wheels that wouldn't clear the big brakes on my car and H&R was on backorder. So I got 1/2" universal spacers at Autozone, like $9.99. They will space your wheels out, but being that they're universal and not hubcentric, they will likely cause a wobble/high speed vibration. At least that's what happened in my case. It was also annoying installing them because the hub hole was so big that you had to sort of tighten the wheels down, then center the spacer and then finish tightening the lugs. Once the H&R's were on the car, all the vibration went away. Plus factor in that you have to buy new wheel studs. There is no way you'll get 12mm without lengthening the studs.

Just get the right ones for the car, you'll save yourself a lot of headache.

 

I've got some spacers 10mm Ichiba and 15mm H&R and both are hubcentric and worked great. I wouldn't go with universal since the center bore is different and you don't want your wheels to shear off your wheel studs :-P. I'm considering selling my used spacers if you're interested PM me.