Say 2 tires both same brand and all, just different sizes

205\60\15
175\60\15

I always thought is was tire width, but a friend is telling me it's not.

are the numbers like this?
width\side wall height\rim diameter

here's the reason I'm asking here. I want to auto-x and my current tires are 175\60\13 I would like to find some better tires.

thanks

 

205 and 175 is the width in mm. 60 is the aspect ratio, 15 the size of the rim.

 

205\60\15
175\60\15

205 will be 205mm wide 123mm tall and 15" diameter
175 will be 175mm wide 105mm tall and 15" diameter

The 205/60x15" will be better for cornering (larger foot print), but might or might not throw off your speedo, and your mpg might suffer due to more rolling friction.

The 175/60x15" will get better mpg, but not good for cornering.