I have recently installed 15x7 wheels with 45 mm offset for the track. The wheels are made by Team Dynamics in England and distributed in US by TeamdynamicsUSA. They weigh 13.2 lbs (I checked them).
For tires, I use 225/50/15 Michelin Pilot Sport Cup R compound front and rear. I removed the plastic trim in the rear fender and the fender liner in the front fender. I rolled up the fender lips using a baseball bat. My car is lowered almost 2" front and back using threaded body coil-overs. I took it to the track for the first time with these tires and I had no rubbing in the back, but when braking and cornering simultaneously, I had rubbing in the front, which I need to resolve. There was no rubbing when cornering without braking or when braking in a straight line. The tires do not rub on the inner suspension parts with 45 mm offset. It might be possible to use 50 mm offset wheels, but I am not certain. (50 mm offset moves the tires closer to the middle of the car than 45 mm offset wheels).

I chose 225 width section tires because that is what Realtime Racing has used on their cars since 1997. They have used 225/50/15, 225/50/16 and now use the mandated size of 225/45/17 in Toyo T1-S. I have looked at their cars and the tires certainly fill the wheel wells. How they avoid rub I am not sure. I do know that this year they are running 900 lb front springs and that last year they won the championship with 800 lb front springs. I also checked 2 ITR's in a local race series and they were both using 225/50/15 Toyo RA-1's (the series tire) I had 450 lb front springs and rubbing. The front camber was at -1.2 degress since I had not had time to adjust it to -2 to -3 degrees which is optimum for these tires. I am not sure this will affect the rubbing I am getting. I can of course raise the car, but lower is better!I want to make the 225's work since others have done it. I am not racing, just tracking my car, but wider is better so why not!