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RV Tire Safety: The tire says “Max Press”. Should I bleed out air?

Many people make the mistake of bleeding air out of their tire when the “Hot Pressure” rises above the number on the tire sidewall. This is NOT correct. Please do not do this.

A clarification might be of help. The pressure number molded on the sidewall of tires is NOT the maximum pressure a tire can tolerate. It is the Cold pressure necessary to support the Maximum Load capacity for that tire. In reality, the pressure number molded on the tire sidewall is the Minimum needed to support that stated “Max Load”.

Increasing the cold pressure above the number on the tire sidewall will NOT increase the tire rated load capacity per industry practice, standards, or guidelines.

With the introduction of Tire Pressure Monitor Systems aka TPMS, drivers now see the temperature and pressure in real-time as they drive. For many, this “new information” can be confusing. But the reality is that tires have been getting warm or hot and the tire pressure has been increasing since pneumatic tires were invented.

Increased tire pressure is accounted for by tire design engineers

If the pressure increases because of increased ambient temperature or because the tire gets hot from being in the sunlight, or the tire gets hot from being driven on, that increase is planned on and accounted for by tire design engineers. The increase is about 2% for each increase of 10° F in tire temperature. Even a temperature increase of 100° F (20° F to 120° F, for example) would only result in about 20% increase in tire pressure. Undamaged tires can tolerate a greater pressure increase than that.

Note: I am not saying that you can heat a tire to above 190° F and not have problems. But those problems would be the result of high-temperature degradation of the rubber and not simply due to the pressure increase.

There are two best practices for setting the pressure. Either set the pressure to what is shown on your vehicle Certification Label. Or set it to what you have learned for your actual tire loading and have consulted the tire Load & Inflation tables to find the minimum inflation required. Then add the suggested extra margin of inflation. I have covered this process in a few of my blog posts available at www.RVTireSafety.Net

Have a tire question? Ask Roger on his new RV Tires Forum here. It’s hosted by RVtravel.com and moderated by Roger. He’ll be happy to help you.

Read more from Roger Marble on his blog at RVtiresafety.net or on RVtravel.com.

 ##RVT1067

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