krazykarl

The questionable accuracy of the TPMS system is why I wish there was a simple way to disable the system or manually correct for the different in the computer reading and a tire gauge. Mine are consistently 4 lbs low in the display, which means I have to run them higher than I would prefer to keep the lights in the dash off.

I purchased a new set of PS4S tires last year and they feel ok, but slow to transition compared to other tires I have run on other cars. That admittedly could be a product of the rear weight bias of the 911, compared to my prior S2000 or current DD of my Mk7 Golf R.

SF997S

I've had mine for a few thousand miles. The 4S are great tires. They're the best tires you can buy right now. Look at any test. They have the longest tread-life, best wet and dry stick, best comfort and they're even warranted. They've been solid in every situation so far.

She had the PIlot Sports when I bought her and for the first few years of ownership, and truthfully for me, I liked those better. They were more sporting. They had less sidewall. They were sharper in the corners. The 4S are more comfortable for sure, but to me anyway, at the expense of some of the sharpness that I would have preferred.

SpecialKay

Thank you, everyone for your thoughts and shared experiences! I'm going to lower the pressure a little bit at a time and report back on how things go. I'm a bit surprised that I'm seeing 6psi increase driving 65mph on asphalt expressway. Granted, the road surface is very hot, but I'm not slinging the car through canyon roads...

Wayne Smith

I routinely see an 8 psi increase when driving in a spirited manner. It seems like a lot. It is what it is.

MrIncredible

Somewhat unrelated but I just put new PS4S on the rear of my .1C2S and it feels very nervous. It has to be related to the tires being new and square vs not "wearing in to the camber" if that makes any sense. It just seems very flighty and makes me nervous to push it in the corners. Has anyone experienced this?

Wayne Smith

I had a pair that made the car slip one way or the other on their own. Finally contacted a correct phone number at Michelin. But that was after a sidewall started bulging. It would appear that there was at least one tire with a problem a few years back. I need to mention that Michelin was wonderful handling this.

Meanwhile, I could get wear of 25K miles rear and 40K miles front with PS2s. On the MPS4S I get 5K miles less.

SpecialKay

Thank you, everyone, for sharing your experiences and suggestions.

I lowered each tire pressure by 1psi. So, starting cold at 72F, the pressures were 33/39 psi. After 10 miles of freeway driving at 60 mph at 86F ambient, the pressures came up to 37/44 psi. and stayed there for the next 10 miles. This couple of psi when warmed up made a perceptible difference, to the better, and I can now feel what's going on with the car and the road. As Rig.Stunts pointed out, these tires are quite sensitve to pressure!

Some reviewers have called out a little vagueness in the middle, and I can now agree with that. They don't hook up instantly like my previous (Bridgestone) tires with stiffer sidewalls, but for GT style driving, I thnk they're going to be fine. I no longer feel the urgent need to swap them out, but I'll probably consider tires from a different manufacturer next time. Michelin, throughTireRack, to their credit, have offered to refund the purchase price of the tire if I return them and purchase another Michelin tire. It's tempting, but I'm not sure what model I'd purchase instead.

Thank you to the forum!

jamesinger

GT3 tire pressures for the 997s was 29/33. Different tires but when I am going up the canyons, that is where I start with cold pressures. When I go on longer freeway drives, I will usually leave with cold 33/37 just to bump it up a bit. ...but I never see any reason to want over 40 hot, or over 40 for any reason. I am not an expert but the tires just seem not happy very obviously once you hit above 40psi.

Liste-Renn

@jamesinger, does your TPMS show a low pressure warning and caution light with 29/33 cold?

How do your tires wear, especially in the middle of the tread?

I have read that since 911 rears carry 60% of the overall load, as well as 100% of traction and a bigger share of the braking on a RWD car, they require significantly higher pressures than the fronts. Also, they will (counterintuitively) prematurely wear in the center from under inflation due to centrifugal force pulling/distorting the tire and making the center tread proud of the outer edges. My tires have always worn dead even across the tread pattern, on every model 911 and tire brand. (My alignments have never varied from Porsche specs.)

My experience with two 911SCs, a 997.1 and now a 997 GTS confirmed that theory.

My GTS door placard and the 997.2 Carrera owner manual recommends (cold) 34/39 with partial load and 37/44 with full load:


I know that tire technology has changed since 2011, but my own 32/39 (cold) pressures ALWAYS increase to 37/44 up on the ACH or Tujunga Canyons in summer. OEM Bridgestones, MPSS and MPS4S all exhibited the identical pressure increase when hot. Also a bit puzzled why a 997.2 GT3 would recommend so much lower pressures than a similar weight widebody Carrera. OEM tires were likely different, but that's a big delta.

I guess I'm lucky that my GTS TPMS has always been within 1 psi of reliable pressure gauge readings.
My 997.1 Carrera was often off by 4 or 5 psi.