180 treadwear tires at a 200 treadwear Auto-x?

[Dr G]

I am planning a new suspension build around wider wheels and tires. I have three tire sizes in mind: 305/30-19 (or 305/35-19) which I know will fit. 315/30-19 which I'm pretty confident will fit, and 325/30-19 which will most likely fit, but might get a bit tight. (this is on the front which is my limiting case)

Problem - the first and last sizes I listed are available in 200 treadwear. But the middle size, which is my preference, is only available in 180 treadwear (Michelin Pilot Sport Cup 2).

Question - if I opt for the 180's and then want to enter a Goodguys auto-x for example, will I be allowed to run at all? In some type of catch all class for people who don't fit any of the standard classes? Or will I be denied entry?

I'm not sure how the rules work, which is why I ask. I am not particularly interested in fitting into a class, as long as I can run.

Thanks.