When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The 2011 997 OEM 235/35/19 and 305/30/19 size had a WIDE range of recommended pressures (29-36F and 31-44R), which is perhaps where some of the confusion about pressures originated. Even that huge range on the chart doesn't include the 37F printed on my 997 GTS doorjamb for max load (37/44).
I just changed to 245/35/19 and 325/30/19 on my 2011 GTS on 9 and 12 wheels (same specs as a 997 GT2RS) and the listed pressures for those tires are 28F 33R. Having never run less than 33/37 on my OEM 235/305 Bridgestone RE50 or their replacement MPSS, this is a bit of a surprise.
Here is the chart for the 2011 911, if you don't want to click on the link:
As always, YMMV!
I suspect those are full load and V>160MPH... I am not interested in full load and autobahn speeds
I suspect those are full load and V>160MPH... I am not interested in full load and autobahn speeds
I do not understand/follow what you posted...the range of 235/305 tires is very wide- I cannot imagine running pressures outside of this range, on street/track/autobahn/fully loaded:
Your 2.3/2.5 (34/37) pressures fall well within the range.
What are you implying?
I do not understand/follow what you posted...the range of 235/305 tires is very wide- I cannot imagine running pressures outside of this range, on street/track/autobahn/fully loaded:
Your 2.3/2.5 (34/37) pressures fall well within the range.
What are you implying?
I'm not implying anything I agree with you
It seems to me that there was a slight misunderstanding.
I meant to say that at pressures 2.3-2.5 the grip is excellent with PS4S
I just changed to 245/35/19 and 325/30/19 on my 2011 GTS on 9 and 12 wheels (same specs as a 997 GT2RS) and the listed pressures for those tires are 28F 33R. Having never run less than 33/37 on my OEM 235/305 Bridgestone RE50 or their replacement MPSS, this is a bit of a surprise.
That’s really low. Does your TPMS warning light on the dash stay illuminated? Mine go crazy if I’m even a hair below 32/36 cold. I like to try to keep them around 34 and 38 cold but one small drop and the car doesn’t like it at all and instructs me to at something like +5 to the rears. Everything has been calibrated to the wheel size and load through PCM, but it’s very sensitive. Much more so than my .1 cars.
Oh, I haven’t (and probably won’t) run those pressures.
Perhaps the GT2 RS is assumed to be on a track and the speeds will generate heat to bring them up to the mid to high thirties.
It is really hard to tell with the recommendations all over the map.
So, there are no shortcuts- just trial and error for each driver to dial in the optimal pressures for your individual wheels, tires, suspension, model, driving style, road condition, wear economy concerns, etc., etc., etc.
Caveat emptor and good luck.
I’ll post my own ideal pressures for my set up…not that anyone is likely to have my car, wheels, tires and driving stye to glean anything worthwhile from the info.
Last edited by Liste-Renn; 09-27-2021 at 04:27 PM.
I went "backwards" and put on a new set of PS2 N4... 18". They track like on rails. My sports car is back. I have run all iterations of Michelin on this car (PS2, 4S, PSS)... including Continentals. The PS2 N is the best tire for me. Even as the 4S keeps winning YouTube tests, I will never put them on my car again. The 4S took the fun out of this car.
IMO, the PS2 N is not noisier and I did not feel the need to tweak the DSC settings. All is very good. BUTT.... yesterday, I was driving over those little raised reflectors embedded in the concrete and tires did a noticeable "whap whap whap" that the 4S did not do. Is the PS2 N a noisier tire? Umm maybe, but not really. I don't recognize any more tire noise on normal pavement and it is not jarring over expansion joints although I attribute this smoothness more to the DSC system than the tires.
Peace
Bruce in Philly (now Atlanta)
100% with you on all of this. The 4S is a compromise. They're so popular around all of rennlist, personally not a fan after experiencing Cup2 first. The Cup2 is still a street tire, people are afraid of it. Gets bad rep for wet performance too. I say people should be more in tune with their car.
I'm not implying anything I agree with you
It seems to me that there was a slight misunderstanding.
I meant to say that at pressures 2.3-2.5 the grip is excellent with PS4S
I agree with these values and your statement about the PS4S. Michelin allows even lower tire presse in case you will not go faster than 250km/h, see attachment. Some feel comfortable with that, I do not. I stick to 2.3/2.5 (unloaded).
Who loves the PS 4S and why? Compares to PS2? PSS?
Peace
Bruce in Philly (now Atlanta)
I love these tires on Pam's GLA45. They smooth out the rough edges of that car.
But on the 997 they feel like they are doing the same thing and this results in a negative.
Then again, after yesterday's 530 mile drive, I'm thinking I really need to bite the bullet and change out the original struts. They've gone over 142K miles and the recalibration of the shock table is no longer holding them together. As Adias pointed out earlier, you need to have the suspension right before you can gauge the tire.
I agree with these values and your statement about the PS4S. Michelin allows even lower tire presse in case you will not go faster than 250km/h, see attachment. Some feel comfortable with that, I do not. I stick to 2.3/2.5 (unloaded).
Image of Michelin's PDF below. Notice the last line (translated) For speed below 156MPH: Front 2 Bar/29 PSI. Rear 2.2 Bar/31.91 PSI.
Yes, but the other recommendation is 37/42- which appears nowhere else that I have seen...
Posted on the doorjamb sticker: the max load front is 37.
Max load rear is posted as 44, not the 42 above- which is speed dependent, not load.
No wonder everyone is a bit confused.
Last edited by Liste-Renn; 09-26-2021 at 08:46 PM.
I think the magic numbers for my PS4Ss so far are 33/37 (for spirited local driving). I still don't think I like these I'm really pissed I didn't listen to my gut and get PS2s. I'll continue to break them in and find their soul.
09-24-2021, 07:49 PM
