I'd like to throw my .02 in here.

I also run the Fuzion ZRi and love them. Best bang for the buck out there. Notice I did not say best performing tire out there. They stick very good, but are a little "uncommunicative". I have even tracked them and they held up very well. However, I would not go pushing them at 8/10's on the street. They have also held up very well for me in the wet as well. Not a track tire at all, but a really good all-round steet tire.

The comparison with 16's vs 17's where the 17"s were faster was due to the increased grip, not the effects on accelration. The 17"s would still accelerate slightly slower than the 16"s, but in this case that effect was outweighed by the increased cornering performance they offered.

 

Ok, let's cut through the FUD.

There are two issues that you're dealing with in upgrading wheel sizes: unsprung weight & rotational mass.

Rotational mass is the most highly recognized issue. The issue is the more weight you have further from the center of rotation, the more effort it takes to change the wheels velocity. The same effect can happen either by adding more uniform weight, or by moving more weight to the outside. This has an impact on both acceleration and breaking.

As an example of this you could put a paint can on a rope and swing it in a circles. Close to you it's not going to have a whole lot of velocity for each rotation. Now if you let the rope out further, the can would have a lot more velocity and be hard to spin faster or stop.

Unsprung weight is the weight of everything on your car below the springs, hence the name. Next time I hear somebody say "unsprung weight makes you go slower" I'm going to explode... Unsprung weight has to do with the effeciency of your suspension, and is similar to rotational mass with a different effect.

The issue is this, assume you have a REALLY light wheel and you go over a bump in the road. Your wheel starts to move upward, and your spring absorbs the shock and pushes the wheel back to the proper distance (and then the shocks stop the bouncing.) Since your wheel is light, the spring is able to counter this motion easily. Now make that wheel super heavy. You go over the same bump and your wheel starts to move upwards again. The spring is pressing back, but it can't because this is a heavier wheel and therefore it's motion is stronger than the springs for a longer period of time. Your springs are now working less effeciently. In order to deal with this, you have to put stiffer springs on the car, which in return means you have to put stiffer shocks on the car to prevent "ricer bounce", which in turn results in a harsher ride in the car. So with unsprung weight you're looking at either a more harsh ride, or a suspension that can't control your wheel as well.

Now that said, 18" wheels are necissarily bad. There are 18" wheels that are extremely light, such as forged monoblock TE-37s. An 18" TE-37 would probably be equal to or less in total weight than OE 17" wheels. However, if you're not willing to spend the money to get a good, light, forged wheel - most 18" wheels are worse for performance since bigger = heavier in most other cases.

 

I upgraded from my AP2 stock 17's to 18" Work rims and see/feel no real acceleration differences.

Granted I don't track my car but I would dare to say that for 90% of the population out there you can't tell the differences.

If you buy some high quality 18" rims/tires I think you'll be fine. Visually the 18's really make the s2000 so much nicer looking

here's a pic of mine (before/after)

 

I am getting 18 Le37T with the adjustable CT springs.

 

whoever is worried about a pound or two per wheel needs to go on a diet!

i see people worrying about "unsprung weight" here and there, and sure, there probably is SOME negative performance, and you may feel a difference between cast 18s that way 25lbs and a set of spoon SW388 when you switch, but how often do you drive on the edge?

if you are concerned about weight, get the lightest 16s you possibly can. if you are kinda concerned about weight, get ANY WHEEL you like. people get WAAAAYYYY to anal about weights. Some posts really can scare the shit outta buyers making them think 18s will make you slower than a bicycle!

It's up to you and your taste! The only set of 17s I would consider are CEs, Forged Emotions, or RGII.

If you really care about weight, keep your stockers, or get a set of rota slipstreams for the track.

My friend is studying to be a mechanical engineer, he has 30lb racing harts on a supra... he still has a 1.3 60', and can break the tires loose at 100mph. Depending on the wheels and where most of the weight is, a heavier wheel can actually render less unspring weight then a lighter one. example = 10 spoke wheel with thick outer edge vs thin 5 spoke with much of the weight close to the hub.
anyways, 1lb extra weight on a wheel will probably never transfer over more that 2.5lbs unsprung weight

so a wheel being 3lbs heaving than stock, will be about a 30lb addition to your car at most drink less beer and more diet coke!

 

Bottom line is do you want your S to be the best sports car it can be, or do you want to go for a certain look?

There are plenty of 17s that look phenominal. But right now there are some trends that are in fashion that require some significant comprimises in performance. Your choice.

IMO you would be smart to get the best of both worlds.

 

It's all about comprimise. I typically consider looks/weight/cost and then pick whatever wheel I think is the best of all worlds.

However, this thread was started specifically to ask about the performance impact, and this isn't a bunch of fanatics spreading FUD. If you're a sporty driver, and you add 5+ lbs. to your wheel I 100% guarantee that you will feel it.

You can't compare to a Supra, they can lay down so much horesepower that you could fill your tires with concrete and still go fast. They are also a heavier car, have a more heavy duty suspension to handle that weight, which can handle heavier wheel weights.

 

I just ordered a set of ultraleggera wheels from O.Z. (18x8 f 18x9 r) w/ BFGoodrich g-Force T/A KDW-2 (best tires i could get with no mod fit) was this a good choice in terms of overall performance? keep in mind i dont race but i do love me some curvy roads.

In other words, was this a good ballance of perfomance and looks?

 

I believe those are under 20lbs, which is light for 18s. Get some thicker tires, and you will notice some added grip - you should not notice a performance change, with such a small change it weight, you would have to be a professional driver on a timed course to maybe notice a 2lb difference

as long as you like them, good choice

(although i'm not a fan of the BFGs)

 

"although i'm not a fan of the BFGs"

same, i was a little upset when they called me and told me i would have to roll
the fenders to fit the eagle f1, i dont want cracked paint. like i said, it was the most grip he(a helpfull man at tirerack) could offer me

thanks, i know oz puts out a light wheel, but i wasnt sure how light stock are.