I just upgraded the tires on my TT from Stock Sized S-02A's to GT2 Sized (235/40-18 & 315/30-18) Michelin PS2's (on Stock TT wheels).

My question is, what tire pressure should I be running for spirited street driving?

I ran 36F/44R on the Stock S-02A's with good luck. Should I run the same on the Oversized PS2's or maybe something lower like 36F/40R?

Thanks,
KJ

 

I run the same tires and keep the pressure about where you were. I would also be interested in other opinions. Anyone?

 

I run 19" 315/25/19 PS2's. I have played with tire pressures and have rested
with 32F & 36R. I have PSS9's and can adjust the dampening stiffer for the street with this pressure without the buckboard ride.
I would be interested to see if anyone has used a infrered Laser Thermometer. Griot's is offering them for $69.99 I am considering one.

 

The GT2 Manual recommends 32F/39R & Standard TT is 36F/44R. It seems like a really big difference. What I'm wondering is if the difference is down to RWD vs. AWD or the tire size (or a bit of both).

Since the TT is supposed to be 100% RWD unless the rear wheels lose traction, I figure that 32F/39R would be good. On the other hand, I've had good luck with 36F/44R and don't see why that would change (by that much).

Thoughts Anyone?

- KJ

 

44 in the rear I feel skips the rear to much. I use a JIC suspension so my preference is 36/40. THis way at full heat up the rear tires only hit about 48lbs and the fronts go to about 40-42. this is ideal and took away any rear skipping on the steet.

Suman

 

I run 19's and suing the 36/44 combination makes the car a little bit loose on fast corners... I set mine to 34/38.. Still loose but better than before....

But then again, if you run too low pressure, then you are sacrificing your tirewear. is the right ?

 

When my tires heat up to temp, pressure goes to 36F & 40R.

 

So I got the PS2's on 2-weeks ago and have played with the Tire Pressure's.

From what I've experienced, 36 PSI is good for the fronts.

On the REAR:
44 PSI - Car was bouncy after hitting bumps on long hi-speed curves (ramps with expansion joints etc.)

42 PSI - Better but still a little bouncy

40 PSI - Much better than 44 PSI in terms of bounciness with a comfortable ride and good balance.

So my vote goes for:
36F/40R

Also, the PS2's are VERY grippy and inspire A LOT of confidence when driving fast.

As for the "High Speed Wallow" that Kiko experienced, I did not experience it ALTHOUGH the softer sidewall vs. the S-02A makes going over bumps less "solid feeling" and a little more bouncy.

 

How do you compare your SO-2A's against the PS2's? I HATE the softside walls so much I'm thinking of going back to SO.2A's or Pilot Sports rib N-rated.

 

You know, you make an interesting observation. I went from Pilot Sports to Pilot Sports 2's and I get a very slight vibration at about 120 mph that I didn't get with the Pilot Sports. Could this be the softer sidewall? Trust me it's not the balancing, I've had it checked and re-checked and then balanced by hand. I've been told that you are going to get a slight vibration at those speeds. What say you?

 

Kiko...get the Yoko..Neovas for 18 or advan sports for 19.s me likey.

 

I remember you mentioning that you had 295's in the back and 225's up front.

I'm running 235/40-18 N3 up front and 315/30-18 N2 in the back. so my observations might differ from yours.

For ultimate grip, the PS2's are far better than the S-02A's. The handling limits are much higher and I can take turns faster now with much more confidence.

Overall, the ride on the PS2's is softer, but I feel that over really bumpy roads, the car "bounces" more on PS2's.

I've gone up to "Go To Jail" speeds with the PS2's and I feel the ride is very stable. The only time I was worried was when I hit an expansion joint on a highway ramp at high speed and I felt like the car bounced after hitting it. After I lowered my tire pressures in the back, that phenomenon went away.

I also noticed that running higher than 36 psi up front led to noticeable understeer.

The other day, it was raining quite hard so I took my car out for a spin and WOW, rain grip was phenomenal. Mind you my S-02A's were worn quite a bit so direct comparison's aren't really fair. But I felt that the loss in grip from dry to wet was a lot less than I thought it would be. I was able to hold my lines better than I thought I would.

As a bonus, the tires are very quiet and are SUPPOSED to have good treadlife (2 things the Advan's I considered didn't have).

If you go with the Neova's like Wross recomennded, I'm sure you'll be happy. But for me, I am very happy with the PS2's and would buy them again.

I have a track day on May 18th, so I will follow-up a little more after I get them on the track.

- KJ

 

Have you tried Road-Force balancing the wheels?

I believe Kiko's problem wasn't so much a "vibration" issue as it was a lack of "stability" at high speed.

Kiko can correct me if I'm wrong.

- KJ

 

Correct KJ,

As KJ says you need to test them in a Road-Force machine to discover they are out of round. If they're within spec Michelin will supply you with new tyres. Contact the seller and have them sorting the problem.

 

One more thing I noticed was that at Full Lock, the front tires BARELY touch the fender liners in the front of the wheel well (my car is not lowered). This is obviously due to the 10mm increase in tire width (on each side) and the 4mm increase in tire height (top and bottom) which eats up 10.8mm of space between the front part of the wheel well.

On certain slopes you can hear the tire rubbing against the liner under full lock.

That being said, as they wear down, this will be less of an issue. Also, at the race track, you are rarely at full lock (unless you're doing a full-opposite lock drift in which case your tires will wear down faster anyway and it won't be an issue anymore).

- KJ