the pdf file shows there are certain restrictions to the 'class' of each vehicle: stock, prepared, modified and race. changing the wheel width and diameter will cause point increment that will bump up the class of your vehicle. say, the stocks are 18x8. you want to run some light 17x9. so far, the changes will include 1 increment for diameter and width.. doesn't seem to matter if you will decrease or increase size. each increment counts for 1 point... you need to stay within 0-2 points of change to stay in the stock class. DOT labeled 'specialty compound tires' (street legal race tires) give a 3 point bump onto your class change... however! the rules do not shed light onto use of different street tires. perhaps you can change your tires without any reference to class change.

i suggest you stick with the stock wheels and possibly better street tires (wider track, stickier compound, lighter and firmer/shorter sidewall), rather than street legal R compound tires. try kumho ecsta mx's or pirelli p-zero neros.. i hear both have really good gripping capabilities without breaking the bank, but their life is short compared to the average street tire.

'03 Infiniti G35 Coupe M6
GTR - R = g35 coupe