Bob Rouleau

Frequent readers of this forum may recall my post regarding the massive understeer of the 997GT3 and RS when driven near the limit.

I experimented with alignment settings and managed to dial out most but not quite enough of the push.

Last week I did 3 days at Calabogie using my new 18 inch Fikses and Hoosiers. Note that the Hoosier would not be my first choice but the Michelin Cup tires in the correct size have not yet arrived.

The change in the car was dramatic. As many of us have suspected, it is all in the tires. The 19 inch so called "Cup" tires do not have as much grip as the 18 inch version due to a different rubber compound and a street oriented tread pattern.

With the Hoosiers the car changed from understeer to oversteer. A complete reversal. Since my alignment had been designed to reduce understeer this did not come as a big suprise.

I had been running the sways full soft in front and full stiff in back. Moving them one hole put the car back to neutral. When I get a chance I will add a smidge of front toe in as well, the car is almost twitchy on turn in with zero toe.

With sticky tires the car lived up to my lofty expectations. It is in a word, wonderful with precise turn-in and neutral handling in all sorts of corners. Hee Hah! Now to see how it behaves on the 18 inch Cups.

A word about Hoosiers - this is the second time I tried them and like the first time, the darn things rotate on the rim. The tires had been heat cycled by Tire Rack and had been sitting on the rims for about ten days... long enough you'd think. For the first session, I went out with 35 lbs COLD knowing that the pressure would increase to 45 or more lbs ( it did). I figured that to start high and bleed down to the 38 range would help prevent the tire rotating on the rim. It did not.

Mooty liked the RA1 - if the Michelins do not materialize I'll try them.

Best,

mooty

bob, this is great to hear.
as i PM'd you before that i was about to either buy a 996gt3 to add to my RS or just sell the RS b/c i never clicked with it. but with my RA1 in 18" the car changed completely. i have factory track setting and it is very neutral with mid corner high speed push and it does push a bit more around slow haripins. at that point i just slide the car or do full lift.

remember, RA1 is not as sticky as hoohoo or mpsc at their best, but RA1 is very consistent and predicatable. you can't have them all.

btw, eric also found his RS transformed after he dumped the 19" cups.

eclou

The Hoosiers took all of the push out of my TT which was sent out of Stuttgart with only -0.4 deg neg camber in the front. I'm not surprised that they would transform your Gt3 into a drift monster

sharkster

you, me and James are the only bay area non blingers that always want 18s eh

amaist

I have a suspicion that Porsche was developing the 997 GT3 and RS on 18" wheels with proper tires. Then the marketoids threw in the 19" because the car looks better like that parked in front of a restaurant.

mooty

email me when the wheels are on your and james' cars.
i like to see them.

and when those nice looking wheels drop to 2800/set, i will take 3 sets.

CWay27

Yeah but now that the RA1 is out of the lineup and replaced by R888, will it be the same...... Too bad mooty got all the rest stashed in is secret hideout

Bob,

now that you're running hoosiers, do you still drive back and forth on them like you did with the MPSC or you switch in and out of the track??

mooty

i have quite a few sets of RA1 stocked.
i dont think they will be phased out that soon,.
from all i have heard R888 should be equal if not better than RA1, but they do cost a bit more.

gt3cup98

I was thinking about running the Michelin Cup Slicks on RS since this is a tire I ran on the Cup car. Is this overkill for an RS that will not be pushed so hard? What is an RA1. I have CCW 18 inch wheels on the way and have not ordred the tires yet since they are out of the Cup Slicks.
Thanks!
Boyd

Bob Rouleau

CWay - I do not drive Hoosiers on the road except to get gas.

Boyd - you can use Cup slicks but you would have to set the car up for them. That means much stiffer springs and shocks and a lot more negative camber. My experiments with race slicks have never worked out on a compromise street/track car. The softer suspension never loads a real race slick enough to get them to work based on my attempts.

Best,

gt3cup98

Bob:
So it sounds like your first choice is the Sport Cups. What are RAI's? I do not plan on changing suspeniosn, etc. I would get another Cup Car first.
Thanks for your input.
Boyd

mooty

RA1 is the model name of a tire made by Toyo tires.

gt3cup98

Mooty:
Thanks! My guess is that you have tried them all. What is the best and what size for the RS on 18' rims.
Boyd

Bob Rouleau

Boyd - I am waiting on Cups in 18 inches - 235 front and 315 rears. Same size as the 996 GT2.

mooty

never ran R888. it's very new for USA
for RA1: 245/40-18 25.6"...............................305/35-18 26.3

mpsc, like bob, you have to wait for right size to show up.