Rear Firewall Question

I covered all the holes in my car with tin that I screwed to the original panels. No problem at NHRA or IHRA tracks. One thing is that the top of your fuel call can’t be higher than the top of your tires. Kim
Is that in the NHRA rulebook? I can't find anything that states that. I'm pretty sure that's not an issue in my car though.
Thats news to me. I'm pretty sure one of mine was higher than the tires, but no tech guy ever gave me any grief.