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TPMS?

Wol747

Active Member
Aug 26, 2017
1,479
836
Tea Gardens
How accurate/reliable are the TPMS indications?
Mine show differences between one day and the next - same temperatures etc - of 3 to 4 PSI up or down. That's each of the 4 wheels one day to the next.
I've no wish to keep sticking air in but I would expect each day would be no more than 1 or perhaps 2 psi difference on a wheel.
 
I have no earthly idea where exactly "tea gardens" is to give you a definitive answer but if you live somewhere with temperature variances, especially in shoulder seasons, your tire pressure will increase & decrease with temperature swings. Driving at highway speeds usually generates enough heat to cause pressure to go up a few psi. All of this is normal. Monitor & adjust accordingly.
 
How accurate/reliable are the TPMS indications?
Mine show differences between one day and the next - same temperatures etc - of 3 to 4 PSI up or down. That's each of the 4 wheels one day to the next.
I've no wish to keep sticking air in but I would expect each day would be no more than 1 or perhaps 2 psi difference on a wheel.
Since the car doesn't display TPMS readings until after the car has moved an undetermined distance it is impossible to use it to take "cold" tire pressure readings. Purchase a quality analog tire pressure gauge and take the pressure readings before the car moves at all.
An analog tire pressure gauge does not have a battery in it.

TPMS was designed to catch gross low pressure readings to warn of low pressure. The trigger for this was SUVs rolling over because of low tire pressure.
 
The above post is correct. You need to take a cold tire pressure reading before driving the car that day and inflate to 45 PSI. You can not rely on the TPMS readings while driving the car. The pressures while driving will be influenced by the heating of the tire and will vary based on weather, road conditions, and how aggressively you are driving the vehicle. The pressure will easily rise 3-5 PSI while driving the car.

Seasonal changes will change the "cold" pressure in the tire, which is why TPMS sensors trigger an alert for me almost every fall/winter to remind me to adjust tire pressure.
 
Since the car doesn't display TPMS readings until after the car has moved an undetermined distance it is impossible to use it to take "cold" tire pressure readings. Purchase a quality analog tire pressure gauge and take the pressure readings before the car moves at all.
An analog tire pressure gauge does not have a battery in it.

TPMS was designed to catch gross low pressure readings to warn of low pressure. The trigger for this was SUVs rolling over because of low tire pressure.
You could just ignore minor swings and drive to enjoy. If it's not 5 lb, it's not worth it. Or if you don't notice it it's not worth it. As the man says, it's mainly to let you know if you've got a flat.
 

Wol747

Active Member
Aug 26, 2017
1,479
836
Tea Gardens
A 10 degree F change in ambient temperature will cause a 1 psi change in pressure. A rolling tire flexes the sidewalls which increases the temperature of the air in the tire. The only accurate way to measure tire pressure is with an analog gauge on a tire that has not moved for several hours.
Yes, I think we all know that: my question was why the TPMS numbers are different each day on the same tyres under identical temperatures: it appears that they are merely "gone flat" alarms.
 

ShawnA

Active Member
Supporting Member
Nov 13, 2017
1,104
860
Edwardsburg, MI
Hi @Wol747 ,

You do not mention whether your car is garaged or not...
I have noticed a 3-4 psi difference on my car on the sunny side
of the car vs the shaded side of the car...
The sensors are fairly accurate.
The real test is when driving at speed after a few minutes
all of your tire's pressures should be very close to each other...

Shawn
 

Wol747

Active Member
Aug 26, 2017
1,479
836
Tea Gardens
Hi @Wol747 ,

You do not mention whether your car is garaged or not...
I have noticed a 3-4 psi difference on my car on the sunny side
of the car vs the shaded side of the car...
The sensors are fairly accurate.
The real test is when driving at speed after a few minutes
all of your tire's pressures should be very close to each other...

Shawn
Yes, always garaged.
 

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