just want to say thanks for the feedback so far...i am finding this to be a very difficult decision...still thinking away

 

I don't have the numbers in my head right now, but if you look at the OEM 17" rims and take note of their widths and offset, this will give you some idea of what you need to get close to with an 18" rim in order for the wheel/tires to fit within acceptable limits.
Let's take the Volk CE's as an example because I do have those numbers and these are considered to be the most ideal aftermarket rims you can get for our car in terms of width and offset.
17 X 7.5 front +50mm offset
17 X 9 rear +63mm offset

If you were to go 18" rims, you would need to get these same widths and offsets (with the corresponding tires to maintain the same diameter overall) in order for them to fit properly. For every 1/2" extra width, you'll need to increase the offset 1/4" (or 6.4mm) so they don't stick out any further than the rim that was 1/2" narrower. Finding 18" with these kinds of offsets will be a challenge. Going 18s will be detrimental in that they are heavier, but also they are heavier further out from the center. This translates into slower acceleration and less top end (if you should care about this sort of thing).

 

ok, 18's are out, only looking at 17's...next step is when i figure out which wheels i like, then i will post again for offsets and tires too

thanks dave

 

SSR makes an 18" wheel for the S2000 that is lighter than the 16" O.E.M's. Again, I am from the opinion that there will be a negligible difference (surely not seat of the pants) between a 17 and 18 inch wheel on the street. Heck, Porsche offers 19" wheels for the Boxster now.

 

Even if they are lighter in total weight, more of the weight will be a bit further away from the spinning axis. Like you say, for normal street use, the effects will be negligible, but imagine what a couple of pounds 1/2" further out would do when going in excess of 100 mph. A wheel/tire imbalance of even 1 ounce can be felt at highway speeds. Granted, I'm talking about an "imbalance", but my point is that 1 ounce has quite an effect. Another inch of rim puts a significant amount of rotating weight under much more G forces.
Porsche may indeed offer a 19" rim package, but then, isn't that Porsche offered with a bit more power, too? Nevertheless, just because a car company now offers a bigger rim doesn't mean that there is no effect on the way the car works. I think they're just willing to accept the compromise for what they'll gain (looks, marketing, lateral performance, etc.).

 

xviper has it figured out. basically, this is how I look at it: if you are simply cruising around town, go for the wheel/tire combo that is going to give you a great look. Try to stick to the optimal offsets so that the wheels don't stick out too far (obviously the exception most of us made/make is on winter wheels, +40~mm is no big deal there).

If you track your car, you really should pay close attention to offsets, wheel size, wheel weight, width, etc. TIRES of course.

I went with the CE28N because I do plan to get into some autox and such, and I wanted a light wheel (I believe they're 13lbs front, 13.5lbs rear) that would fit the car properly. (The last thing you want is rubbing).

If I were just cruising around, not racing the car, I'd go with a set of 18's for sure.

Of course, there are custom wheels available in whatever sizing and offsets you desire (Kinesis for example)...

 

[quote name='xviper' date='Feb 7 2005, 04:09 AM'] Even if they are lighter in total weight, more of the weight will be a bit further away from the spinning axis.

 

I've seen your pinky, ol' buddy!

All kidding aside, for those with "street cars", wheel size and weight is not an issue. "Looks" is by far more important and I think our good friend, Vlad, is a "cruiser" anyway. He combs his hair while driving.

 

Personally, I'm not going to order wheels until I KNOW that there will not be a noticable decrease in acceleration. I'm also waiting until I see xviper's Mercury Silver Volks in person to see if they look as good as I think they will.

 

I think your red S2000 would look amazing with gunmetal volk wheels (either CE28n's or LE37's). Possibly even that new "hyper black" or whatever finish they just introduced.