96C4S

Theres alot of talk about 19 inch wheels have a big effect on the handling of the 993. Has anyone ever tracked and timed their car with 18s and then done the same with 19s or is this just all heresay.

ca993twin

You'd have to be sure to use the same tire compunds and the same overall diameter (ie... a shorter sidewall on the 19" tire), and be able to do the switch a few times on the same day with the same conditions to have a valid comparison.

For the very little this is worth, Rufus with 19" wheels handles way better than Waldo did on the same width 18" kinesis wheels. But there are many variables... Ruf suspension vs Pss-9s, wider (and better) tires on the Ruf, etc. I'm thinking that Lewis Hamilton could probably tell the difference in a valid comparison, but most of us mere mortals can't really tell. Just one guy's opinion.

96C4S

I agree 100% Steve.

Turbodan

I agree with steve for most of his comments, but I think Fernando Alonso or Michael Schumacher would be a better judge than Hamilton (the punk kid). I have heard that the 19s don't do well on the track vs the 18s. are the r compounds even available in decent 19" sizes? I don't think that I have seen 19s at the track. even the ALMS cars use 18" not 19s. what do the f1 cars use (I think it is 18's)? if the 19s were better they would use them.

ca993twin

Danny is correct that the tire choices are very limiting in the 19", especially on an AWD car where you have to be so careful with front/rear sizing. I have found the perfect sizes for me: 255x30x19 front and 315x25x19 rear. This seems to leave me with two tire choices: Yokohama Advan Sports (~$1800 out-the door) or Toyo Proxes T1R (~$1300 out-the-door). Yokohama are a good, proven commodity... I wish I knew more about the Toyos.If naybody has any advice on the T1R... I'm all ears. No R compounds in these sizes. Zip. Nada. zilch.

As far as F1... they have very fat, tall tires on quite small wheels (their brakes are inboard). The tires ARE their suspension.

I have to use 19" wheels because I have massive, 15" Ruf brakes... they won't fit under an 18" wheel.

More data to consider.

96C4S

Steve the 255 fit with no rubbing issues i have 235 now and 315 i think its to big of a gap personally

pstoppani

IMHO, there are more reasons not to use 19" wheels than there reasons to use them. Not only are 19" sizes limited, but they are also more expensive than 18". 19" wheels are heavier than 18".

Really, the only performance reason that would justify 19" wheels are brake fitment, as Steve pointed out.

sfbanchs

when i picked upo my 997tt wheels compared to the original turbo twists the 997tt wheels felt around the same if not a hair lighter

Bob Rouleau

There are NO decent R compounds for 19 inch wheels yet. Why anyone would want 19's is beyond me. Metal weighs more than rubber after all. Buy 18 inch Michelin Cups and be happy/ The 19 inch version is basically a street tire in spite of the name.
Best,

chris walrod

What does Lewis know, he's still rollin' on thirteens

ca993twin

96C4S wrote:
"Steve the 255 fit with no rubbing issues i have 235 now and 315 i think its to big of a gap personally"
You forgot the question mark, but I think this is a question. Yes the 255x30 fit perfectly without rolling the fenders or a particularly aggressive front camber. No rubbing issues at all. I agree with your assessment, and think that 235 & 315 is a recipe for understeer... some of which can be dialed out with sway bar adjustments or agressive camber.

Pete wrote:
"19" wheels are heavier than 18".".
Some are heavier, some are lighter. The light ones are very expensive.

Bob wrote:
"Metal weighs more than rubber after all."
Uhhh... which metal are you thinking of. Magnesium is far lighter. Even plain old aluminum is lighter. Actually, if you check tire rack for the weight of tires, they are generally far heavier than the wheel they'll be put on. Unless you are using a non-DOT legal racing slick... those puppies are very light.

If you are planning on R compounds... you will not be happy with the few if any choices available in 19" at this time. That, to me, is the biggest negative for going to 19".

WHB Porsche

It seems like many of the 997 GT3 RS guys have switched to 18" wheels and noticed BIG handling differences, in a real good way. It depends on the car. And regarding the lightness, Steve says some 19s are lighter than 18s. This is true. But the SAME make/model wheel will always be heavier in 19 than 18.

Bob Rouleau

For track and R compounds 19 inch rims are a must. There are no decent r compound tires in 19 inches at the moment.

As to the weight of rubber - compare the weight of two equal wheels, one 18 and one 19 inches then compare the weights of two identical tires, one in 18 and one in 19 inches. The sidewall is not the heavy part of a tire. Today at least 19 inch wheels are for bling and 18's are for go.

pstoppani

Looks like the swtich to 18" is mostly positive based on this thread: https://rennlist.com/forums/997-gt2-gt3-forum/369859-gt3rs-understeer-cured-and-how.html

pstoppani

typo: I think you meant 18 inch are a must