Ari 997TT

I got in the car today and flipped the dash display to the tire pressure screen. It showed pressures of 32 &33 psi front, and 41 & 42 rear. I checked manually & found front pressures of 35.5 both sides & rear pressures at 43 both sides. Do any of you know whether this discrepancy is within normal limits for the system?

B-Line

Ari,

In my experience, tire pressure changes from gauge to gauge. What I try to do is use one gauge, and dial in my TP with the knowledge that my gauge either reads low or high.

My point is, the TPMS may or may not be "accurate" but if can drive and feel, where the TP feels good, then you can remember the settings on the car and always return to those numbers.

B

AAHTT

mine always reads 2-3 points lower than the manual gauge and I have tried several gauges with the same result, it is also annoying when it tells me to add air to a tire when the pressure is not really low.

texas911

Mine is spot on with my digital tire gauge.

PorschePhD

mine never is and often throws the damn light. PITA

Terry Adams

I will miss the lack of this 'feature' in my 993.

docjackson1

ari-your experience is similar to mine. if you use 4 different gauges, you might get 4 different readings, all depending on the accuracy of the gauges. i would just use the tpms as a trend analyzer (losing pressure in one tire-picked up a nail?) or to show that you are gradualy losing pressure and need air.

mastiffdog

My TPMS reflects higher than my digital gauge.

I have TPMS on the Z06 and on my BMW R1200GS Adventure motorcycle. I use the same gauge (a Sears Craftsman digital) on all three vehicles. I find the Vette and the bike are nearly dead on with the digital gauge, so I know the P-car's is reflecting higher. Therefore, for the Porsche, I rely on the hand held gauge and not the car's system.

george_k

My TPMS reads exactly 3 psi less than the actual pressure on all 4 tires (checked by 3 different digital and standard gauges) last time I had the car in for service I had the dealer check this out and the service tech claimed the reading is accurate. He did say the system can be calibrated. next time I am there, I will bring my own digital gauge to show them that the TPMS is not accurate and ask them to calibrate the system.

docjackson1

george-i agree with your advice-i am also about 2-3 to the low side. i am also from nj-who is your dealer-schneider?

eclou

Something interesting I discovered when switching the TPMS sensors from my stock wheels - the actual sensor holes were not set in the correct orientation at all from the factory. The Beru tech articles specifically state that the holes must be pointing radially OUTWARD from the wheel. What I discovered on my stock wheels were they all were pointing radially INWARD towards the wheel. My stock wheels never read correctly. My aftermarket wheels with the sensors mounted by myself in the correct orientation are actually within 1 lb of my digital gauge. Just an FYI

ALPINE_997

I have experienced the same thing with my 19's. It was throwing faults when it shouldn't have.

I use the TPS reading and not the gauge reading due to the fact that the gauge reading accounts for outside temp as well. Please correct me if I am wrong so I can smack my tech

With the new wheels I just put on they are dead on with a new set of sensors. I put them at +1/0 and with a digital gauge they read true to +1/-1 which is close enough for me.

george_k

doc, My dealer is Ray Catena in Edison.

george_k

My original 19" wheels were also off by 2-3 psi, must be something wrong with the receiver or the PIWIS programming. I don't know if it's possible to re-calibrate either of these units.

Frino

TPMS and my AudiSport tire gauge are always in synch. TPMS stays on my display all the time.