RobC4sX51

So you started at 28/31 cold? I start w 29/33 and see 38/41 after a 25 mins session at 85F OAT. The 41 is a bit greasy but any less and the edge of the rear tires take a "beating"! I drive to/from DEs on my track wheels/tires (currently Pzero but switching to Conti Extreme Contact Sport soon). Also, at my experience (instructor/A group) the stock pads don't cut it. Clark @ Apex recommended Padgit PS-29 (yellow) which I like except they do squeak towards the end of light braking around town. Slotted vs drilled rotors are also better for the track heat cycles. FYI.

JCtx

Keep in mind Porsche TPMS typically runs 2 psi low, meaning if it shows 33, it's actually 35. Could be different, so it pays to compare against a calibrated gauge. I don't like anything above 35 hot, but it's largely a personal matter... but it still pays to play to find the optimum setting for your car and performance level.

Jabs1542

Funny but you just described my problem with the MPSS. If the pressure was on the low side it would roll the tire and chew into the shoulder, and if I had the pressures on the high side they were quite greasy. This made it very hard to balance the pressures because the acceptable window wasn't very large. MPSC2 solved that problem

BTW +1 on the slotted rotors.

Jabs1542

Mine are within 1 psi of my Longacre gauge, which is plenty good for a quick check going down the straight. Remember, our TPMS will not read certain pressures like 33, 37, 41, etc (I think that was them) due to the bar to psi conversion in the system. So it could alarm you by showing one tire at 36 and the other 38 when in reality they could differ by less than 0.5 psi (i.e. 36.4 shows 36 while 36.7 shows 38).

If you've checked your TPMS against a gauge you trust and they are off by +2 psi then you are good to go, just remember to apply your adjustments (the -2 plus knowing the bar to psi round off) when you check the TPMS on a straight.

randr

This is largely accurate - on PZero N1 I start at 28-29/32-33 and monitor closely. They are a road tire and need the air to keep the sidewall in shape.

very different kettle of fish to track crossover tires or dedicated track tires which have very stiff sidewalls - thus you drop the temp before you start and then build to operating temperature.

OP - Do not deflate road tires for/prior to track use - its an internet myth and will simply destroy your sidewalls and shoulders quick smart.

Jon D

HenryPcar

Get yourself an infrared temperature gun (HF sells them cheap). The air pressure you want varies depending on the track and temperature. Start at a higher value, for example 34/40. After a few laps, pull in and measure the temperature with the infrared gun on the width of the tire. Take 3 reading between the inside, middle and outer edge where it contacts the pavement. Over inflation will give you a higher reading in the middle grooves, whereas under inflation will show higher reading on the inside and outside grooves. You want your temperature between the inner, center and outer tire thread to be the same. This way you are getting full grip for the track, car and temperature for that day. The ideal air pressure is quite dynamic and you want to adjust it accordingly.

phx991

I've never seen TPMS readings that were more than 1 psi off from my Longacre gauge, and even that is rare.

Jon D

chuck911

Five gold stars for you. One for concentrating on hot pressure. One gold star for ignoring cold pressure, and another for mentioning the increase from warm and ambient temp. You get a fourth gold star for winding up pretty darn close to perfect. And I award your fifth and final gold star for pointing out the tires running at this temp held their grip all day long.

My only quibble is the greasy comment, which can't be helped really, that is just the way everyone talks. Tires of course do not get greasy. They get hard and lose traction however when they get overinflated, something that happens all the time to guys who go by the cold pressure they set in the morning instead of the one they are actually running on the track. Which is the only one that counts. Which you totally get.

Well done.