Tire Pressure

What are the recommended tire pressures for the MPG 184 RV

Hi MGOK,

Take a look at the sidewall of the tires. It'll give you the max cold inflation. Cold means 70(F). If you check pressure in the morning, not in direct sun, with temps around 70, the pressure should be set to what's stamped on the sidewall.

If temp is 50, you'll want to subtract 2-3 psi.

Direct sunlight will give you a reading that's higher and is misleading.

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It may also be on the data label that lists all your weight limits (usually on the driver's side of the trailer near the front.

danemayer said:

If temp is 50, you'll want to subtract 2-3 psi.

Direct sunlight will give you a reading that's higher and is misleading.

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I have experienced this recently. Getting ready to hit the road, air temps in the 40's, one side in the sun, the other shade. Temperatures and pressures seem to varry a lot (20 - 30 degrees and 7-8 psi). Do you pull out on the road, and stop to check again before the tires heat up to highway temperatures? What's the formula, PV = nRT? I wonder if there is a chart for what the pressure should be at given temperatures. I have seen it written in more than one place that for every 10 degrees in temperature the pressure changes by 1 psi. This is not what I have observed, more like 2 - 3 psi for every 10 degrees.

Fill the tires to the max on the sidewall and drive it they will be ok.

From the Goodyear Recreational Vehicle Tire Care Guide:

The effects of temperature and atmospheric pressure.
Air temperature and atmospheric pressure effect tire inflation pressure. If the outside temperature increases 10oF,
tire inflation pressure increases approximately 2%. Conversely, when the outside temperature drops 10oF, the tire
inflation pressure lowers approximately 2%.

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Using the 2% temperature rule, and a cold inflation of 110psi on my Goodyear G614s, at 50(F), I would reduce the pressure by 4% of 110, or 4.4 psi. On E-rated tires with normal inflation of 80psi, at 50(F) I would reduce pressure by 4% of 80, or 3.2psi.

danemayer said:

From the Goodyear Recreational Vehicle Tire Care Guide:


Using the 2% temperature rule, and a cold inflation of 110psi on my Goodyear G614s, at 50(F), I would reduce the pressure by 4% of 110, or 4.4 psi. On E-rated tires with normal inflation of 80psi, at 50(F) I would reduce pressure by 4% of 80, or 3.2psi.

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That would be more in line with what I have observed when I knew the inflation was pretty even. TPMS showed the tires to be 80 degrees on the sunny side and 50 degrees on the shady side with pressure differential being 5-6 psi.

By the gas law mentioned above pressure and temperature are related P1/T1 = P2/T2. These are absolute pressures and temperatures. 70F + 460 = 530R absolute temperature. 50 + 460 = 510R absolute temperature. new pressure at 50F will be 510/530 = 0.96 times the pressure at 70F. A change of about 4% for a temperature change of 20 degrees F. 2% for a change of 10 degrees F. 2% of 110psi is 2.2psi. 2% of 80psi is 1.6psi.
If my tire pressure is at max sidewall pressure at 50F, I leave it alone and don't worry about it rising nearly 2psi at 70F. Tires will tolerate a little more pressure and less flex than a little less pressure and more flex. I have seen where tire manufacturers recommend adding 10psi to the sidewall max on ST 65mph tires to allow running at 70-75mph. So I believe more pressure, a couple psi, will not be a problem.
Fuss about pressure being too low. Don't worry about pressure being a few psi high. I have never seen a tire that had air enter and overpressure a tire, but I have seen them where air left and pressure dropped. My concern is losing pressure over time, not increasing pressure.