Tire Air Pressures & TPMS

[LaPlaya]

I received my TPMS today and got it installed fairly easily. I had the tire pressures checked at my tire dealer and he said all the pressures were set at 90 PSI Well, not according to my TPMS. The pressures range from a low of 83.3 to a high of 89.5 Who do I trust ? Hopefully my TPMS is correct. Should I buy a compressor and air them up myself ?

[wilpower]

LaPlaya wrote:
I dont know where to take it to be weighed in my neighborhood

I don't know about Canada, but in the States, most truck stops have scales. For $7- $8 you can get axle weights, at least that will be a starting point.

[rockylarson]

TPMS sensors have a specificity range. Some as high as +/- 4%. Means same tire at 100 lbs can give different sensors readings between 96 to 104. Possible same sensor on same tire repeated several times 96-104? I don't know. I do know my three "quality" gauges would read 97, 100 and 103. Which is correct? Doesn't matter. Close enough for good-to-go.

[LaPlaya]

I have not had the opportunity to weigh my motorhome. I dont know where to take it to be weighed in my neighborhood (Midland Ontario) I am going to Niagara Falls Ontario in a week. I could look for a place down there or along the way. There is a place nearby but it would only give me a gross weight and I believe that I need individual weights.

[luvlabs]

Even "top opf the line" pressure gauges can be off. They can easy be plus/minus 3 psi. My really good gauge reads 2.5 psi high when checked against a calibrating gauge.

My TST sensors are +/- 2 psi from my gauge - this acceptable to me.

[Dennis_M_M]

I set mine at 65 with a good gauge, then I look at the Pressure Pro and they run between 60 & 62 (14 tires). So now I have my base line. Who cares if they are off a pound or five, If I see one dropping below 60 (which is rare), then I check it.

[okgc]

bluwtr49 wrote:
Temp makes a big difference so it it was warm when the dealer aired them up and it's a bit cooler when you checked....that would make a difference. Mine vary by 10 psi just due to temp.

X2
Now that you have a TPMS you will notice how much tire pressures change due to tire temperatures. A tire with sunshine on it can increase 5-10 compared to tires in shade on other other side.

[bluwtr49]

Temp makes a big difference so it it was warm when the dealer aired them up and it's a bit cooler when you checked....that would make a difference. Mine vary by 10 psi just due to temp.

[Ivylog]

How long ago did the dealer put them ar 90? Without weighing why 90?
I'd take the highest reading sensor off and put it on different tires and see if it agrees with the previous reading for each tire.

[J-Rooster]

BB_TX wrote:
I would get a good pressure guage and check them myself.

I agree a top of the line pressure gauge will give you the correct readings!

[linnemj]

Just installed a TPMS today too and had the same issue. Checked them yesterday morning with a good gauge and filled all to 70 psi. The TPMS is showing them at 67 to 68. I am thinking it may read a little low.

[wilpower]

Pressures can vary depending on the gauge they used to air up. Get a good air gage, and check them yourself. Also they should be set according to the weight of your unit, if you don't have the weight, go by the pressures on the info label by the driver's seat.

[BB_TX]

I would get a good pressure guage and check them myself.