I submitted a letter in support of the IT to Prod allowance, so I should know this...but I'm not sure it's 100% official yet. And as noted, it would need to be an IT car in IT trim to be a true crossover car, so you are correct, no real slicks allowed, must be on DOT rubber. As soon as you call it a Prod car, or use one Prod allowance beyond IT prep, you'd need to at very least comply with the Prod safety rules, such as the IT optional 7th and 8th forward cage members, fire system, and window clips. I may be missing something, check the rulebook.
Will