I no longer offer tire service so I have partnered with two top tier shops to get the wheels out with tires. They will also have 6UL's available by themselves of course. If my site shows out of stock, try them!

Goodwin Racing
San Diego, CA USA

Phil's Tire Service
Cragsmoor, NY USA

Both of these shops specialize in competition set ups and can get you the tire combination you need.

The pic is Goodwin's shipment. A bunch! We both have 15x7.5's now. I'm sold out of 15x8 6UL's until December but he should still have quite a few available. Phil's Tire Service in New York has a few sets of every size in silver and I think one set of black 15x9 6UL's.