tian647

I recently added a set of Carrera III's to my car in 18x8/10 running RE-11s, in place of Cup IIs running Conti DWs (not DWSs) - besides more available grip, the ride on the same suspension is actually more controlled and smoother on the new 18s. I was pleasantly surprised.

Christian
'95 Carrera

callipygian 911

While I can't tell any difference in acceleration, I can discern an enormous difference in cornering grip since my 18" wheels accommodate wider tires than the 17" ones.

CalvinC4S

I personally prefer 18's as the 17's feel squishy to me.

kreeshp

Thanks, Mike, for the insight. Also glad to hear that there's no perceptible difference, if one chooses the right combination of wheel and tire.

What got me to assume that it would be an increase in weight when switching from 17" to 18" is the mention made by the OP that he was considering 18" RUFs which are virtual boat anchors as compared to the stock Cup II's.

mpruden

Ditto. This is my exact experience. Targa, swtich to 18"s, no problems, no funny symptoms of added weight, no feeling of added bumps.

Perhaps a more experienced track driver could feel the difference, but it all just feels "right" to me.

993KT

I thought the cup II are 18 lbs front and 19.5 lbs rear. I have had some 18" BBS LM wheels on my car for a few weeks and I went back to 17" because I didn't like the ride and feel of it. For me the selection was mostly based on look, cost, and feel. I think any performance merit (on street driving) is mostly a placebo effect.

nine9six

Rufs are heavy compared to MOST wheels, and I dont for a second buy into Alois Ruf's statement that the additional unsprung weight of Ruf wheels assists in straight line stability. They are however, attractive wheels; but I for one, am not to keen on the idea of bolting boat anchors on all four corners of my car.


Calibrated butts have nothing to do with it...The physics of rotating mass/weight and moment of inertia dont lie...

nile13

"The laws of physics will be upheld in this house!" (c) Homer Simpson.

The question here is, will a driver feel it? The answer, for me, is: "not really"

Kika

When I went from cup IIs to MY02s, I noticed handling and ride changes.

Can't say there was any difference in acceleration or not, but steering response was crisper, and the ride was a little harsher.

That may have also been attributed to tire and tire pressure differences though and NOT just the wheel difference. The cup II tires were Sumitomo HTR Z IIIs and the MY02s had Michelin Pilot Sports. I had them mounted at the shop and don't know what pressure their in the Michelins.

Incidentally, the Cup IIs and the MY02s are pretty close in weight, don't know about the tires.

H.H.Chinn

The difference would probably be more appreciable if you went from the 17" to a 19" wheel than just the one inch to an 18".

nile13

I believe that both are direct result of shorter sidewall. With results exactly as expected.

Tony.CO

Don't dismiss the fun factor!

It's fun to pick out 18 wheels that suit your style, making the car feel a bit more tailored to your personality.

Buy at set of 18 inch wheels/tires at fair price, keep your 17s until to your ready to let them go knowing the ride/feel has met your expectations. You can always sell the 18s too if not.

Edward

I will concur: "feel" is due largely to sidewall and one's tire choice. Go to an R-comp in 17", say, and you'll know all you need to know about stiffness and will likely forget all about the need to go to an 18" (just a point of comparison, not that I advocate an R-comp for street use ).

There is much to be said about the light weight of the Cup IIs, not to mention their simple, elegant lines. I submit most want to go to bigger wheels more for looks than any real consideration of function. So if aesthetics are the chief concern, just go with what you like since at street speeds you'll likely notice no diffs in handling between 17" and 18" wheels, but will almost certainly notice a diff in comfort.

BTW, may I humbly submit that the stock Cup IIs ain't hard to look at




Edward

orangecurry

How much? There are a few factors to think about. I notice it. I have tried/own most of the OE wheel sets.

1) weight - whether or not the driver notices, increasing the rotating weight is a bad thing - it will blunt acceleration, braking and, well, everything. 17" wheels and especially tires (which are furthest away from the center of rotation and therefore have a big effect) are usually lighter then the wider 18s

2) width on the front - the biggest difference that you notice immediately is the feel of the difference in width between 205 and 225 section tires - for track or road, the steering precision of the 205 is almost telepathic compared to the (also heavier) 225. Sure a 205 has less grip, but there's plenty of grip on a 993 anyway - if you are driving at speeds where this becomes an issue, then you should be enrolling with an F1 team.

3) Feel - a great deal depends on tire choice - for example Bridgestone S-02s have a very hard sidewall, so 17s wearing 205/50 and 255/40 will feel 'precise' allowing good turn-in and driver feedback. Softer sidewalls will feel like marshmallow in comparison. Yes 18s with a shorter sidewall tighten things up in this respect, but see 1) and 2) above.

No matter what you want to do, keep the OE so-called Cup2 wheels. You will go back to them one day and immediately think 'wow - this is the best wheel/tire combo ever!'

Kika

Having made the jump from cup IIs to MY02s years ago, primarily for looks, I absolutely agree. In retrospect, I wish I had kept my cup IIs in storage, just so I could alternate as desired. Since I don't have a lot of storage, I didn't keep them. It is a good looking wheel, classic look, relatively lightweight and always looks right on the 993.