Tire Pressure on Class B

[LK23]

I just purchased a 2023 PleasureWay Ascent. Before departing the dealership, I asked about tire pressure and they could only recommend look at the door sticker that says 52 psi front and 70 psi rear. Before departing, I checked the TPMS on the dash display and it said you cannot check the tire pressure until driving. After I left the dealer the TPMS read 65 psi front and 78 psi rear.

I contacted PleasureWay about how to read the tire pressures when cold and they told me to call Mercedes.

I called Mercedes and the person was clueless.

Questions

1. Can you check the tire pressure on the onboard TPMS when tires are cold and not driving?

2. Should I use reduce my tire pressures to the psi listed on the door sticker? Or, should I have the vehicle weighed? Most use will be just my wife and I with very little stored onboard.

[Mike8253]

Don't specifically know your RV, but if you have valve stems, you ought to be able to read each tire's pressure. For the moment, set your pressures to what your sticker says when your tires are cold (morning at ambient temp and before you drive on them). Next, get your tire manufacturer's recommended psi-to-weight chart to know what your inflation should be for the weight the front and rear tires are carrying. Then on your 1st trip when you are at your travel weight with a full tank of gas, get your RV weight at a CAT Scale so you know specially what your pressures need to be. Don't neglect maintaining proper tire inflation.

[LK23]

Here is a followup on what I learned.

I had my PleasureWay Ascent weighed and based on the Michelin tire charts the air pressures should be

Front: 40 psi
Rear: 50 psi

The door post reads:

Front: 52
Rear: 70

The factory or the dealer had inflated my tires to

Front: 65
Rear: 78

I reduced the air pressure to the Mercedes door post of 52/70.

I called Mercedes and, strangely, there is no way to see the tire pressures on the TPMS while parked. You have to drive it to see the tire pressures. This does not make sense because you should read your tire pressures while the tire are cold and not after being driven.

[code2e]

Originally Posted by LK23

Here is a followup on what I learned.

I had my PleasureWay Ascent weighed and based on the Michelin tire charts the air pressures should be

Front: 40 psi
Rear: 50 psi

The door post reads:

Front: 52
Rear: 70

The factory or the dealer had inflated my tires to

Front: 65
Rear: 78

I reduced the air pressure to the Mercedes door post of 52/70.

I called Mercedes and, strangely, there is no way to see the tire pressures on the TPMS while parked. You have to drive it to see the tire pressures. This does not make sense because you should read your tire pressures while the tire are cold and not after being driven.

The tire pressure sensors are inside each wheel. They are battery powered internally. In order for the batteries to last, the sensor is motion activated. So, there is no way to read tire pressure on the monitor until the wheels have rotated a short distance, activating the sensors. No need to warm up tires.

Your monitor is powered from the chassis battery. Motion activating the sensors gives them a battery life of up to 10 years. If they were constantly active, they would last 1-2 years. Replacement requires pulling all tires and at least breaking down the beads to access sensors.

[Mike8253]

Originally Posted by LK23

Here is a followup on what I learned.

I reduced the air pressure to the Mercedes door post of 52/70.

I'm confused. (It happens often.) How do you air up your tires? And how did you read the pressure as you reduced it to 52/70? I'm obviously missing something here.

Looking at the Pleasure-Way manual, you can read/increase/lessen air pressure in your tires at the valve stem. Why do you have to read the pressures via your TPMS to properly set them for your travels? One other note, you are better off using a single, quality tire gage to consistently set your desired pressure across all your tires than relying on four different sensors to provide their independent assessments of tire pressure. TPMS should be used first and foremost as a warning tool for air pressure loss. I have a good TPMS on my MH, and none of them read the same no matter how I carefully set the pressures in each tire.

[LK23]

When the vehicle was purchased last week, it had

Front: 65
Rear: 78

I reduced the pressures to

Front: 52
Rear: 70

And, it drives much better now.