so what do these numbers even stand for?? 195/45/15 (i see other variations as well)
okk i know what these numbers mean now : )

what rims would fit well on my '07 fit?
obviously if the bigger one fits, i'd rather go with that one. but i'll decide that afterwards.
and btw, my fit hasn't been lowered yet.

currently looking at either:

Rota Circuit 8
Size: 16x7"
Bolt Pattern: Dual 4-bolt (4x100 & 4x114.3)
Offset: +40
Finish: Gunmetal with Polished lip
comes with 205/40 tires (whatever 205/40 means =\)


OR

Rota GT3
Size: 15x7"
Bolt Pattern: 4x100
Offset: +40
Finish: Royal Gunmetal with Polished lip
doesn't come with tires, but if i was to get tires, what size do i need to get for it to fit?

 

I think you need to do a lot more research before you look into wheels.
Google can help.

 

The 40 mm is the offset of the hub face to the vertical centerline of the wheel. In other words the wheel/tire is pushed outward toward the fender arch. But doesn't quite get there except as follows.
The 15x7 wheel with 40 mm will fit ok with 195/55x15 tires and maybe the 205/50x15's but the 16x7 wheels with 40 mm offset will rub when fitted with 205/45x16 tires.

 

quick tire 101. the first number is the width in mm's. the second number is the aspect ratio. meaning the percentage of the width of the sidewall's height. so a 205/40 is 205mm's wide and 40% of the width is the height of the side wall. meaning the side wall is 82mm high. you can then convert this into total wheel height. you multiply the sidewall height by 2. then divide that number by 25.4(to convert from mm's to inch's) then add the diameter of the wheel. so for example a 205/40 r 16 come up to a total diameter of 22.45" and stock is 23.44" so that is 1" smaller in diameter than stock. it will most likely accelerate faster than stock but you'll be putting more miles on the car and have to go a faster speed to keep up with traffic.

you can actually use your stock fit sport tires on the rota gt3's if you wanted to.