The section width isn't a number you should concern yourself with unless you're worried about clearance. The Tire Rack lists tread widths too, that's what you should be looking at. Some tires have almost no difference between tread and section widths, other tires have a large difference, with the tread being significantly less. Also with a 245 vs a 225 on the 8" rim, the 245 will be somewhat pulled in at the sidewalls when compared to the 225's, making the difference in width somewhat less than numbers indicate.

I'd warn against T1-R's, they're not that great. I've heard of people chunking or otherwise damaging them at autocrosses on Miatas, without doing anything out of the ordinary. Those are light cars, so I'd immagine it'd be worse on a heavier FD. If that happens at an autocross I'd hate to see what happens on track. They've also got soft sidewalls for lousy turn in. They're also not in the same league in terms of grip as most of the tires listed. They'll be on the bottom of the pack in terms of performance.

GoodfellaFD3S is right about a lighter tire being more apparent to acceleration than a lighter wheel, unfortunately it's harder to get a light tire with the characteristics that you want than it is to get a light wheel with the characteristics that you want.

 

The 245/45 section widths are measured on an 8" rim, so they do not need adjusted.

While it's true I should care more about tread width than section width, there's no good way to measure tread width. You can put two tires together and see which has more effective tread, but no good way to consistently show that with a measurement. This is why I didn't include the few tread width numbers I found.

The chart does have tires ranging from a performance street tire to a moderately aggressive race tire. Anyone who might refer to it should definitely be familiar with the grip/rain/durability/temp characteristics of each tire. Since that was subjective, I didn't put that on my spreadsheet.

Dave