Rim/tyre choice for performance
 

Ok so i have the stock 16 inch rim (comes on the base gt model)

This rim weighs 15.9 lbs according to reports and comes with a 205/55 16 tyre

i had planned to upgrade to enkeis http://www.tirerack.com/wheels/Wheel..._19&sort=Brand

which weigh 18.2 pounds.

The tyre i would use would be the continental extreme DW.

the question is since the 16' wheels weigh 2lbs less each which would perform better the 16' with 205/55 conti tires or the 17' with 215/45 tires

I would say the 17's since you are putting a slightly wider tire on, that will get a bit more grip. And the fact that you're going to a much lower profile tire will help take the flex out and keep you planted.

I wouldn't worry about the weight at all. The other thing to consider if you really are hung up on the weight, is how much the tires weigh. You might find the bigger, but lower profile 17 weighs slightly less. I'm grasping here but I think you get my point.

Any other thoughts?

Define perform..

Accelerate Corner and Brake better.

Basically looking at unsprung weight vs increased tyre contact patch.

RPF1's, 17x8 weigh 15.6 lb., 17x9 weigh 15.9 lb.

Continental DW weighs 20 lb. in 225/45-17, 22 lb. in 245/40-17
Michelin Pilot Super Sports weigh 22 lb. in 225, 23 lb. in 245

235/40-17 might be a very good tire size, but not many make/model options in that size.

Saw the rpf1's but not liking the styling.

not really looking to go beyond 225 tire size

O.K. no Enkei RPF1, so how about one of these:

Kosei K4R 17x7 14.0 lbs
Kosei K4R 17x8 15.8 lbs
O.Z. Alleggerita HLT 17x7.5 15.4 lbs

A little heavier, but look great: Enkei PF01 17x7.5 = 16.8 lb., 17x8 = 17.4 lb

CE28N 17x9 +43 5x100 with some grippy 245/40-17

Probably it's the best wheel choice for low weight, strength, and big brakes clearance

Ok some great rim choices here. Much thanks guys :)

Are Kosei rims strong?

They just cost three times as much as an RPF1.

They're not particularly resilient, no, but they're very affordable. I'd be careful with potholes, but otherwise not worry about them daily driving.

they make one of the most popular spec miata rims so i think for what youre doing, they will be alright.