My wheels are 19 x 8.5 +42. I’m not looking to roll the fenders. Are 15mm spacers the right choice for a semi flush fitment?

 

We need pics to even beginning to hazard a guess... why don't you mount those wheels and post some pics?

 

What would pictures tell you that actual wheel specifications don't? Unfortunately, I'm not able to install them as I don't have tires mounted yet.

 

Not that simple. You need a few big friends in the back to truly test clearance. Not a problem that a case of beer can't fix.

 

To me the eyeball is the best measure oh how wheels look, and how flush, tucked or poked you want to go. I'm not a techie-wheel guy, so maybe it is possible to figure it out from the width and diameter, but since it's got to please my eyes, the eyeball test is best for me.

Good luck! And post some pics when you're done!