Self explanatory.. I want to know if I can fit a 225/50 15 on there, and not have any issues on a slightly lowered ITR?

Tried searching to no avail.

 

......depends on the drop, offset, and camber.

It is possible to get a 225/50/15 on there, though.

 

If you're looking for better performance, concentrate on getting better, stickier tires, rather than wider tires. For example, a 205/50-15 Azenis RT-615 tire is perfect on 15x7 wheels, and will give you way better performance than some other street tire in 215 or 225.

If you're already talking about R compound tires for track use, though, that's a different story...

 

I'm running 205-50-15 Azenis on my 15x7 TE37s (+43 offset I believe) still... been working great!