TT Surgeon

Just switched to these R tires, 225 fr/ 295r, what do you guys like for pressure on a C4S/TT platform?
I was thinking 36fr/39r hot, others have suggested 40 hot all around on a awd car. FWIW, I use the X73, -1 camber now. TIA

Bill_C4S

Chris - somewhat lower pressure...say 33f/35r hot

jrgordonsenior

Chris this was discussed here a few weeks ago so you could do a search and find lots of opinions from that thread. There were lots of opinions from drivers who don't have the heavy platform you and I do. Michelin's recommended pressures of 34-36 hot are fine for cars weighing under 3000lbs, but those temps eat up your rears on a heavier platform like yours/mine. I 've ran these tires exclusively this year and have gone through 5 sets of rears so far, on my second set of fronts still. I firmly believe the rears need to be 40-41 hot, while the fronts are fine around 34-35 hot. Any less in the rear and you'll cord the outside shoulders quickly. It is also especially important to get them up to temp before you start taking turns at speed. They also beg for some serious camber, just look at how the treads configuered for inside tire traction. I'm running neg 3 up front, 2.5 in the rears.

They're great tires, just get em hot( I start by driving in a straight line in the back of the parking lot for a few runs) before you start putting pressure on the shoulders.

swftiii

Just like the others have mentioned above - I shoot for 34 font and 35/36 rear when hot.

-Skip

ColorChange

I agree 100% with JR.

Bull

On my C2S with -2.2 to -2.5 front and rear, I have gone through 4 consecutive sets of MPSCs, 235s and 285s. I target 36 hot all around, and have gotten very even wear front to rear, with the fronts usually going just before the rears.

Actually, when I manage the temps dilligently and rotate the tires after each event, I find the tires need replacing from too many heat cycles before I cord them.

Patrick

If mine (185 30 18's) get above 40 in the rear, it gets real greasy. From what I've seen, peopple running the 17's don't have this problem.

993RSCS

I also ran 36 hot rear/34 hot fronts for about 4 sets of Cups with even wear on my TT.

Paul

ColorChange

This information is directly from Michelin for a 996.

Rear axle slip angle:
Decreasing the rear pressure will increase the potential of the rear axle
Little effect on rear axle slip angle from front pressure changes
Overall vehicle handling behavior and cornering attitude:
Big effect from front pressure changes
Steering gain decreases 20-25% between 26-38psi
Small effect from rear pressure changes: increasing the pressure will tend to reduce the understeer slightly
Overall recommended hot pressure targets:
Front: 32-34psi
Rear: 37-40psi

Morty

Website in Swedish, but click the link for the PDF file:

http://www.pcsracing.nu/tips/index.a...etaljer&ID=139

May provide some guidance on MPSC pressures.

Bull

That is identical to my experience.

jrgordonsenior

These different experience may have to do with tire and rims sizes. So what size rims widths and tires sizes is everyone using? I'm on 315 rears on 11" wide rims.

Bull

I'm on 8s and 10s for rims, and 235s and 285s for the MPSCs.

911

JRG and I experienced a similar thing w/ these rears a few months ago at the Streets. When I first got my MPSCs I ran them way too low (hot 35 in the rears). Then I went to 40 (hot) and the car felt so much better and I immediately dropped a second on my time, and more importantly, the tire wasn't rolling over. I'm at neg 2 up front and 2.5 neg in the rears, btw.

Bob M

On my 996TT at GingerMan, I used MPSC's (225/40-18s and 295/30-18s) with pressures of 34Fr / 35Rr. For reference, my best lap was in the high 1:37 range. The surface temps were within 1 to 2 degrees across the full width of the tires and I observed the best wear patterns I have experienced yet on these tires (my 3rd set) .

Some of the temp preference differences expressed can be attributed to suspension setups, don't you think? It seems to me that tire pressures a stock car needs verses one that has been lowered, uses upgraded adjustable shocks and adjustable sway bars needs for optimal handling performance would be different. Throw in individual preferences for how one likes the car to "feel" and you will likely have a range of what works best for a given car/driver combination. But, I do not have the level experience at this that many of you have so maybe I am way off base with this line of thinking? Just the same, I liked what I got out of the pressures I used that weekend.

Bob