Just thought I would share my experience with Slabs and 37" Nittos.
I have been running this setup for roughly 4,000mi now and actually just had two tires replaced by Discount Tire Direct.
When I first mounted all of the tires, all 5 took minimal weight on the balancer (no more than 4oz on any wheel), but one tire had a noticeable wobble and it was felt in the steering wheel. We put that tire as the spare and DTD planned on shipping out a new tire once they were back in stock. Fast forward to my first rotation (only a 4 tire rotation) and the wobble came back. Turns out another tire had a noticeable wobble on the balancer and only became noticeable on the vehicle when the tire moved to the front axle.
DTD had just received a fresh shipment of Nittos and promptly sent out 2 new tires. I mounted them last week and now have zero vibrations and I haven't even had them balanced yet.
As a side note, I have been to a couple America's Tire stores here in the Bay area and have not had any issues getting them balanced. That said, they will not touch mounting them and understandably so.
Could not be happier though with the Slab/Nitto setup!