I need a couple tires and the other tires on the fat fives I'm going to use are 195/55R 15. I really don't want to get 55 series, if I got a pair of 205 50R 15's and put them up front, would the sidewall size be about the same? The rears will need tires fairly soon and I would like to go to 205's but if there's that much difference in sidewall height I might just go with some 55 series tires.

 

205/50/15's are have a noticiably shorter sidwall compared to 55's. I had 195/55 and went with 205/50's and it got some whell gap all around now. One advantage other than the increased with is that with the 205/50's your gearing will be alittle shorter, so that gets a from me.

 

I got 205/50/15 in front
195/50/15 in rear.
There is a noticable sidewall difference.
My friend didn't notice it though. He likes 35" bfg's though.
In your case i think the difference will be obvious.
If you plan on buying new tires get what you want and don't worry
about how it looks.

 

the 205s on the front only will give you a more sure footed feeling when turning into corners.
check the autocross forum for more info on this subject

 

I'd say go with a 195/50/15, works really nice on an EF.

 

http://www.miata.net/garage/tirecalc.html

 

Wow that's what I call a GREAT util. From the looks of it, the difference is going to be next to unnoticeable!