TJ&LadyDi
RVF "Dinosaur"
In getting ready to hit the road this weekend, I did my traditional tire pressure check. The coach had been sitting for several months due to the pandemic, so I was curious what I would find.
We use an EEZ Tire TPMS unit, so I switched it on and let it find all the tires. It was a perfect day to do this; cloudy and in the mid-60s. I checked the tire temperature with a digital infrared thermometer and they ranged from 59 to 63 degrees. A four-degree spread is insignificant, so I was off to a good start.
The TPMS display showed tire temps within a couple of degrees from what I got with the digital infrared thermometer. Again, an insignificant difference. Pressures all read 2-3 pounds under what I regularly set them at (except one that displayed 5 pounds low); not bad after several months of inactivity, but they needed touching up.
So, I broke out the Milton Pro Digital pressure gauge/inflator and fired up the shop compressor. The Milton unit has been checked against two known-to-be-accurate gauges and it has always been spot on. Checking the coach tires, I found them to be 2-5 pounds low; a bit of a difference from what the TPMS showed, but not too bad.
I aired up each tire to the pressure I normally use (Newmar-recommended after four-corner weighing: 110# steer and 85# drive/tag)...plus a half pound. The Milton digital gauge/inflator reads in tenths of a pound, so a half-pound is easily doable. I add the half pound to compensate for the small amount of air leakage that occurs when the TPMS sensor it's screwed on.
I went back into the coach and turned the TPMS unit on again. After allowing time for all the tires to register on the TPMS display (about 5 minutes), I reviewed what I found. All tires were now shown on the TPMS receiver as being within one pound of each other; five read one pound lower than the Milton gauge read and five were the same as what the gauge read. Close, but no cigar when compared to an accurate gauge.
Conclusions.
- A TPMS is a very useful tool for RVers, but it is not a tire pressure or heat gauge; it can be off by 5# or more.
- TPMS sensors on the tires vary in accuracy. Mine were within one pound of an accurate tire gauge, but I have seen them off by 2-3 pounds.
- Carry spare sensor batteries and a couple of spare sensors in case one fails.
TJ
We use an EEZ Tire TPMS unit, so I switched it on and let it find all the tires. It was a perfect day to do this; cloudy and in the mid-60s. I checked the tire temperature with a digital infrared thermometer and they ranged from 59 to 63 degrees. A four-degree spread is insignificant, so I was off to a good start.
The TPMS display showed tire temps within a couple of degrees from what I got with the digital infrared thermometer. Again, an insignificant difference. Pressures all read 2-3 pounds under what I regularly set them at (except one that displayed 5 pounds low); not bad after several months of inactivity, but they needed touching up.
So, I broke out the Milton Pro Digital pressure gauge/inflator and fired up the shop compressor. The Milton unit has been checked against two known-to-be-accurate gauges and it has always been spot on. Checking the coach tires, I found them to be 2-5 pounds low; a bit of a difference from what the TPMS showed, but not too bad.
I aired up each tire to the pressure I normally use (Newmar-recommended after four-corner weighing: 110# steer and 85# drive/tag)...plus a half pound. The Milton digital gauge/inflator reads in tenths of a pound, so a half-pound is easily doable. I add the half pound to compensate for the small amount of air leakage that occurs when the TPMS sensor it's screwed on.
I went back into the coach and turned the TPMS unit on again. After allowing time for all the tires to register on the TPMS display (about 5 minutes), I reviewed what I found. All tires were now shown on the TPMS receiver as being within one pound of each other; five read one pound lower than the Milton gauge read and five were the same as what the gauge read. Close, but no cigar when compared to an accurate gauge.
Conclusions.
- A TPMS is a very useful tool for RVers, but it is not a tire pressure or heat gauge; it can be off by 5# or more.
- TPMS sensors on the tires vary in accuracy. Mine were within one pound of an accurate tire gauge, but I have seen them off by 2-3 pounds.
- Carry spare sensor batteries and a couple of spare sensors in case one fails.
TJ