As was mentioned stay away from shaddy companies. IMHO I would go with HRE. I have several sets since 1999 and the company is top notch in service and product. They have specs on file from various XLR owners and will work with you as-to what you want. You have a high end Cadillac so why not match that using a high end wheel. Granted, you can purchase off the shelf "brand X" wheel, but the wheels are often times "universal" or generic thus issues down the road.
Personally, I like the old style HRE wheels and you can find them on Ebay used. Look for Corvette HRE wheels. Ask for the sequence numbers on the back of the hub, and then call HRE for the details. Once you get the okay from HRE then they can fit the wheel to match your XLR. I had my set re-tweaked to my XLR and I can't be more happier! Check my thread for specs used. The best combo are the 19/20 sizes if not 18/19. The prices range from $1500 to $3,000 (that's half the price new). Try to purchase the best looking set with least about of damage, because replacements range from $200-250 depending upon the lip sizes and if it's the inner or outer barrel. If the center piece is damaged....RUN!
You can also buy used Iforge wheels too, but using the same caution as mentioned above. Most of my friend have HRE wheels. If you check other exotic forums it's mostly HRE with some using Iforge with little or none using "universal" off the shelf wheels. Now back to XLR talk.
Option "B" is to use Corvette wheels. Check the Corvette forums for they are on sale all of the time, but make sure of the off set. The same holds true for our XLRV wheels. Maybe somebody here has a set they might want to sale? Either way, it's a win-win for the OEM 18" are very, very skinny (235) and the XLRV wheels are wider and taller (19" 245 or 255?). The Corvette's are staggered and come in different styles.
Here's the link:
https://www.xlr-net.com/forums/cadi...re-543r-testing-clearances-on-2007-xlr-6.html
You'll find the spec on the same page. As I stated call HRE and they will help you. Ask for Nick. Also, there is a set on Ebay (I think it's over now?) that is a 19/20 combo, but two of the inners needs replacing.