M3S3R

Can any one let me tell me why I'm getting warning light on dash at speeds above 170 mhp. When traveling at high speed normally over 170 I get some kind of warning coming on. Something regarding tires.
I checked my tire pressure and its in the normal range front and back. Its not great getting warning lights at that speed because your paying more attention to the road, than the warning being displayed on the dash.
Has any one else had this issue? If so how did you correct the problem. I hate having to back off the gas to read a warning light that then go's out. Ask my dealership and they had no idea what the issue is.

JR956678

I'm sure others will chime in, but you don't mention how the "normal range" is determined. If you're running "Comfort pressure" there's a 165MPH maximum speed and a warning if you exceed that. To run the speeds you are running you need to be using "Full Load" settings which are higher. See the owner's manual.

Jim M.

What ^ he said. Change your tire pressure setting in the multi function screen from comfort setting to full load. Had it happen to me at exactly 170 MPH. You will also have to run the higher tire pressures too.

Randyc151

The other posts are correct, "Comfort Pressure" mode is for speeds below 165, and I see that warning every "good" lap at VIR, too. The options are 1) run the car with higher pressure and lose cornering grip, 2) ignore the message but run a couple of more PSI than you'd ideally like (what I do, and I see the warning but don't let it bother me), or 3) put a cap on yourself at 165mph. I'm not sure, but you might be able to set the car to "full load" setting and ignore the suggested pressure changes, since we have to do that anyway in "comfort". I'm looking forward to any other suggestions on this, too.

JR956678

I think Jim and Randy both have answered with responsible answers to the issue. Underlying why the TPM works the way it does is that as a tire flexes - due to the load it's carrying - heat is generated. The faster you go the less time the tire has to dissipate that heat so it gets hotter. As rubber gets hotter it starts to degrade, and eventually can (and will) fail. I once had a catastrophic failure of an under inflated rear tire on a MB E series sedan and the entire sidewall separated at 70 MPH - a full 100 miles from the start of my trip. The reason it lasted 100 miles is that my speeds were not that high in the beginning and the weather was cooler and it took that long for the rubber to degrade sufficiently to fail. Eventually traffic got lighter and we got on the interstate and could go 70 MPH and reached the point of failure. Fortunately my wife was able to control the car and get off the road and neither of us were hurt but I have to admit - it scared the c**p out of both of us. Totally my fault for not checking tire pressures before we started the trip. (This was in the days before TPM)

Another factor is that the aero packages on a Porsche increase downforce which creates more tire sidewall flex and generates more heat which degrades the rubber even faster. So - running a Porsche at 170 MPH on under inflated tires for those conditions is taking a risk. If the speeds over 165 MPH are brief (ie the fastest part of a track and only for a small amount of time) those risks are lower - but still present. I think this is why other posters have mentioned not only setting the TPM so that it doesn't alarm but actually increasing the tire pressures to some happy balance between the risk at high speeds and the loss of cornering grip. There's nothing wrong with the TPM system or its programming - it's simply telling you that for those speeds and increased downforce loads, you need more pressure in your tires to keep heat from building up and weakening the tire enough to fail. Having had a predictable failure at 70 MPH has made me quite certain I don't want that experience at 170 MPH.

JR

Randyc151

Also, these cars are tested, certified, and shipped with P Zero tires. I decide to believe that the Cup2 tires I run are more designed/engineered for high speeds, and thus can handle a higher speed limit than the manufacturer builds into the TPM software for comfort pressure. Also, as JR points out, I am not over 165 for more than a few seconds per lap at VIR, so I have learned to tune out that particular warning. I glance to make sure that it's not flashing a brake overheating problem when I can, but it all happens so quickly in a monster brake zone, I don't always catch it.

M3S3R

Thank you for all the replies and the manual say to change out of comfort setting if traveling above 165mph . In the 997 Turbo I did not have this issue. I guess its a good thing to have the warning.
Easy to change the setting on the dash max load. So are most of your running 38 pounds in the front and 48 pounds rear for the street. For the track your tires would get really greasy with that high of tire pressure. I would think
most would start with say 34 and 44 cold on the track, maybe even a few pound less.

Randyc151

There are other threads that go into tire pressures, but generally I and many others completely ignore the Porsche tire recommendations. They are total BS, and the dealers are the biggest culprits. I picked up my last car with pressure set at 42f/48r!! It really seems incompetent, but that is what the dealer set it at. Thats also in the full load setting.

So here's my suggestion: Totally ignore Porsche and your dealer when it comes to tire pressure! Actually ignore all auto manufacturers when it comes to this aspect of cars. They are all touting the high tire pressures to cover them in the worst case, most freakish situation possible. And they are sacrificing grip and ride quality the rest of the time to do that. It goes back to the lawsuits that Ford had with Firestone tire failures back in the 90s, but they play it safe legally when advising on this. I guess if you are towing a 40' speed boat with your Porsche at 190mph, and loaded down with coolers of beer in the boot and all passenger seats, then the 38f/48r would be the only time applicable.

I suggest at MAX on the street, cold 34f/38r in comfort mode. Just leave it there and forget it. I run my tires (at VIR, which is a high speed track) 30-32f/32-34r hot. That means I go out as low as 24f/26r and do some warm up laps, and sometimes I have to come in and bleed pressure to get back to those parameters. Some guys will run them even lower than that for better grip, but at over 165mph I like to have some added pressure for the high speed areas.

M3S3R

Problem solved go to TPC settings and don't check comfort or max load. Leave them both blank and set you tire pressure. You will not get the warning light for low tire pressure. Tested this during the weekend and it worked for me. So happy not to have the warning light come on at speeds over 165mph.

Randyc151

Are you saying the tire pressure monitor does not give any pressure warning at all? Did you just leave it on TPM display so you could watch pressures? The last thing I want is to have a tire going down and not know until it doesn't turn.

ace37

I tried that and thought I ended up with a low tire pressure light on all the time because my rears were at "only" 38 psi or something like that. For street use I'd like a light to come on perhaps when tire pressure is below 30 psi. I added pressure to turn the light off but couldn't see any way to set the threshold differently from what Porsche decided on.