Apex Late

Quartermile,

Can you give us all the offsets and the suspension settings. -3 is a fairly significant number on the stock suspension. I would like to know what you are running front and rear from both a caster and camber perspective. Additionally, I would like to know if you had to make any modifications to achieve these numbers. I would really like to run the set up that you are talking about.

Lastly, if you were running at the track, do you know if your lap times were improved?

Mikey

Guys if find my last alignment sheet I'll scan it for you. There are no spacers, just bolt-on. Can't tell you what it's worth at this point since it was my fist run at Buttonwillow and I had additonal mods during this run. I'd say they are worth 2-3 seconds over stock tires due to 15% increased patch area and R compound.

NJ-GT

the wider the tire, the less negative camber to be run all other things being equal.

Ask me how I know...

Apex Late

NJ-GT,

Ok, I will be the one to ask.......How do you know?

ben in lj

have you ever or do you plan to run T'hill w/ it?

NJ-GT

Switched from 295 MPSC to 335 RA-1 on the stock wheels running -2.5 negative camber rear.

The car was driving like shhh....t. It felt like no having rear sway bar combined with no having rear shocks. The car was dangerous actually.

Contacted a lot of people to find out the same answers: tire pressure, is the alignment ok?, are the tires deffective?, what setting on rear sway bar?, bla bla....

So, I decided to talk to a shop that races a Viper Competition Coupe with a similar setup (275/335 RA-1). They told me to go with a wider wheel or reduce camber.

Due to the wider tire and -2.5 camber, the outside section of the tire is not even touching the road, as soon as you turn, there is almost zero spring rate while the outside of the tire makes contact with the road. Basically, there is no load on the outside sidewall and too much load on the inside sidewall.

Now, you'll know why the race cars running very wide tires don't have that much negative camber as compared to let's say a GT3 Cup.

Mikey

Ben, it's long haul to NorCal with the muffler as loud as it is. This month I'll be running at Willow a couple of times, Spring Mountain (Vegas) first week of June. NorCal tracks once I get a trailer -- though the 4 runner lease won't run out for another 6 months, so T'hill next year.

NJ-GT, Hmmm ... no funny stuff, just a hint on one part of the track but it could be I am just forgetting what the camber setting is at ... it may be -2.5

Phokaioglaukos

Currently I have the OEM Pirellis Rosso tires in 235/40 and 295/30 with 1.2° of camber in the front and 2.0° in the rear on the OEM wheels. I'm getting more wear on the inside of the rear tires, but the fronts are wearing evenly. Of course these tires do slide a bit.

Time for new tires and I plan on Toyo RA-1s. For the next event I plan to leave the alignment where it is and check tire pressures and temperatures so I have some better data. (The RA-1s like high 30s to low 40s PSI hot and 160° to 220° F.)

Based on these posts I was planning on 245/40 in the front and 335/30 (if they fit, otherwise 305/35) in the rear. The installer will try both rear sizes but really doesn't think the 335s will fit.

I'm a bit concerned that if the 335s do fit in the shop, either that they will rub under load on the track or they will limit what I can do with an alignment to something less than optimal.

I'd appreciate your advice!

NJ-GT

I ran 335 A3S05, 335 RA1, 315 MPSC, 315 MPS2, 315 V710, 285/680 Dunlop slicks. No one of them rubs on my car.

Now the funny part: The 315 V710 rubs on Z06's GT3, the 285/680 slick doesn't fit on JerseyBean's GT3, the 315 MPSC rubs bad on my friend Rick's GT3. Some people reported ABS issues running Cup car slicks, while my car doesn't trigger the ABS at all regarding of my tire combos.

The 335 fits on the 11" wheel, but it goes better on a 12". Who's supplying the RA1? I'm looking for a fair deal on them.

Phokaioglaukos

I'm talking to Dave at CJ's Tire, a new sponsor of Riesentöter PCA:

LIMERICK
1405 S Township Line Rd
(off Ridge Pike adjacent to Wawa)
Voice: 610-409-0400
Fax: 610-409-5642

Z06

With the V710 315 a weekend at the track and it never rubbed, but on the drive home it did.
My big problem was the ABS failing, it senced the large gap in tire diameters.

I will try the V710 285 as to NJ-GT recommendation. the Hoosier 245/315 R6 is on order.

Phokaioglaukos

Not a lot of happiness, yet. Installed the 335 rear tires and almost got home, but they do not clear the fenders and on hard compression they rub. Turned around and had them replaced with 305s. Same issue on hard compression, such as when the car goes over a big bump. I'm thinking the "ski jump" after the bridge at Shenandoah will be a big issue this weekend, but we will see. I'll talk with my alignment shop tomorrow. The rears only have about 1-1/2 degrees of camber....

NJ-GT

Chris,

In order to run wider tires, you also need plenty of negative camber. I just ran 10" front wheels with Kumho 285/30R18 and 12" rear with 315/35R18 (pretty tall) last week. No rubbing at all front or rear. My car was raised last week to 105mm/118mm that's 10mm below Euro specs, I was running too low before.

By the way, my slicks are mounted on 996TT wheels (11" ET45) and they don't rub either.

You can still roll the fenders (baseball wood bat ), I haven't done that yet because I haven't needed it so far.

I'm going to try this setup at Pocono East in two weeks.

cgomez

That's a nice setup NJ!
Now, do you know if that same setup will fit my 997S?
I'm planning on buying track wheels and definetively want to go as wide as reasonable up front. At least 9 or 9.5" or maybe 10" as you did?

Will also do something to "fix" the camber up front. -0.8 only is just a recipe for destroying tires too soon.

9Eleven

The tire rack site indicates that Michelin Pilot PS2 in this size tire 315/30YR18, will fit the rear for a Gt3, the below listed cars are for this size 265/40YR18 XL, tire will fit the front. Can you get a shorter tire? Maybe a 35YR for the front? If the car is mainly for the street, will there be any issues? I guess if this size tire can fit the below listed cars, it should fit under a Gt3, eh?

265/40YR18 XL

2005 Porsche 911 Carrera Cabriolet 997 Chassis
2006 Porsche 911 Carrera Cabriolet
2005 Porsche 911 Carrera Coupe
2006 Porsche 911 Carrera Coupe
2005 Porsche Boxster
2006 Porsche Boxster
2005 Porsche Boxster S
2006 Porsche Boxster S
2006 Porsche Cayman S