SCCA A/X rules questions about class and OE stock vs mods, main question is about tire and wheel size changes Options

[DRPHIL914]

I was online looking a local events and trying to find some A/x events in the
South Carolina or North Carolina region,(i live in SC near Savannah Ga, but my son lives in Charlotte and we frequent the area)
Anyway i found out on i thing the event list on Motorsportreg.com that there is a regular A/X events up in Charlotte region, and took a look at the rules and classes etc, and was wondering if anyone here was doing that up there or even somewhere else could guide me in the registration process , and, answer some questions about if i can run the tires/rims i have or do i have to purchase other wheels to run the proper class.
In the rules and class descriptions i notice they say you have to run rim size and width that would have come on that model for the year?? but what about diameter etc too?

My 75 914 has the stock 2.0 L motor all original and stock, except i did the PMB Performance 5-lug upgrade with stock rotors and calipers etc, i currently have 16" fuchs rims with 205/55-16 tires(that are same diameter as a stock set up but much wider) i have 6" on front and 7" on rear. So my question is , to run in the stock un modified street class would i have to source a set of 15" x 5.5" rims for the A/X? I could do that they would then be same size and width as the stock rims that came on the car, just would use 5 lug rims not 4, but that should not matter as long as i have same specs.
I just dont think i want to be bumped into a modified street class just because of slighly wider tires, so please advise.

thanks for any infor and direction you can provide.

Phil.