So would it be worth it to go 19" for the looks? Does it make that much of a difference in performance or should I get the 18"? Yea rafa I'm going to get the black ones on my b6

 

I have 19" just waiting for the snow to melt, I got them for the looks. If the roads are really bad and you reallycan't avoid driving on pothole ridden streets, maybe 18" would be better. As far as performance goes, seriously, how much track time/racing do you do yearly? I know my car is my daily ride and I'm not going to start drilling holes, removing my rear seat, etc... to shave a few pounds for the difference it makes in my day to day driving (I guess it depends on what you need, personally, I don't need a dedicated race car).

 

i had some lighter weight 18's and they were great.

 

Its not in the weight of the wheel. Don't have any idea where that comes from. Its the overall diameter of the tire that is the factor. As the tires circumference changes it changes your over all gear ratio. Higher the tire the less power. Keep the over all diameter as close to stock as you can and your gear ratio will remain the same.

 

If your more interested in Looks and can deal with only the smallest loss in gas milage then go for 19's i am, ive got them all picked out i sut needs to decide what banki need to rob to get them (5g's for the package) its been said b4 but yur going to gain wieght from the wheel but lose some from the tire since you are not gona have the same hieght of sidewall, im looking for 225x40x19 i think stock is 215x55x16 its a negligable difference but the waty the car looks and the way girls like cars who the F**K really cares about an extra 3 lbs per wheel. Get the wheels enjoy the car do the girls end of story.

 

What weighs more metal or rubber? If you are increasing the amount of weight then it makes it harder for the engine to spin it. Also the over all diameter will affect this.

Here's an example of what happens;
Me and a co-worker had the same car (gtp) with the same mods but he had 18's and i had stock 16's. We raced and i would walk him 3 lengths, but when he put on the stock rims i would only have him by 1/2 a length.

 

This may sound weird but I have heard if you get a different size rim for you car it will throw off your speedometer? Is that true LoL! (for example: your going 50 but your speedometersays 55 or vice versa) Is there any truth to that?

 

use this calculator (http://www.miata.net/garage/tirecalc.html) and it will tell you the difference at the speedometer (you have to know the tire size for the rims)

 

Its like a rule of thumb 17"s for speed 18"s for some speed and some style 19" for style

 

This is a stupid analogy. for your comment to make any sense the person would have to have no tires on the wheels - for tires the diameter, circumference should be the same, doesn't matter if you have 15's or 19's

If you change the analogy to "imagine a mouse trying to spin a 10lb rim versus a 20lb rim how much more power would be needed to spin the larger" that would be true

If I race you with a 16" rim and it weighs 15lbs and I have 19's that are really expensive light weigh models then we would be more of a comparison.
In conclusion size doesn't matter