Is it ok to do it, or is it going to affect something, like through of the TCS or something else?

 

you can do it. optimally you want to preserve the stagger. If you have 18s, go 245/40 front and 245/45 rear. factory stagger with equal width tires to reduce understeer.

 

I plan on doing this on my track wheel/tire combo so I can rotate my tires. It shouldn't throw tcs off.

 

i actually want to go with 19s, what would i need to obtain factory stagger with equal width tires? Thanks for the help. And one more thing, what would be the difference with putting widder on the back than on the front?

 

anyone?

 

TCS does not like having the same diameter tires on all four corners. If you can get a lower profile for the front in the same width, you're fine. I prefer to have the same size all around so I can rotate the tires and to get rid of some of the understeer. To figure out what sizes to get, you can compare at http://www.miata.net/garage/tirecalc.html
The site works great and its free

 

I've driven and autoX'd a whole year now without stagger. No issues with the VDC. In the summer I run 245/40 all round and in the winter I run 215/60/16 winter tires.

Great setup. It allows you rotate and remove some of that front push. IMO, it also makes the profile look better making the car more balanced.