Are Our Tires REALLY that sensitive?

Effy wrote:

mike brez wrote:
I weighed my rig once loaded up how it will travel. Inflated tires 5lbs over what inflation chart says for my weights. Check them every time before we leave. Have a tire pressure monitor system of some sort. At home when we park we park on rubber mud flaps.we don't cover our tires but is most likely a good idea.

Never understood the 5-10 PSi over the chart thing I see on here all the time. Why? If the chart says at x weight adjust to Y PSI, why would you go over? 10 miles down the road once they heat up now you are way outside the parameters specifically outlined in the chart. I don't get it. Over inflated tires can be just as bad as under-inflated. Why wouldn't you go by the chart?

Lets stick to discussing the "cold" inflation. If your cold inflation is correct for your actual tire load and you aren't exceeding the speed rating for your tires (normally 75 for Motorhomes with TBR or LT type tires or 65 for ST type tires on trailers) the tire will function within design limits when hot.
The Load / Infl tables provide the MINIMUM recommended cold inflation needed to carry the load. Cars basically come with a 12% to 20% extra margin over the minimum. SUVs usually have a 5 to 10% margin. SUVs with a 1% margin can have problems as this margin goes negative with 4 people inside, but that's a separate issue.

I and others know that a majority of RV have one or more tire in overload condition and that's why we strongly recommend getting your RV on a scale. We also know that unlike cars RVs can have significant side to side imbalance and that's why we suggest getting corner weights so you are not misleading yourself into thinking you have the needed minimum inflation when in reality one or more of your tires is probably overloaded.

Once you know the actual load on each end of each axle the proper MINIMUM inflation is selected from the tables and all tires on an axle should have the same inflation. Now the above does not give you the same margin you have in your car. In fact it may give you no margin at all.

Now if you want to avoid a lot of unnecessary hassle I suggest you add a 10% margin to your minimum inflation. That way you probably can go months without the need to add air. Of course running a TPM is extra insurance that something unusual hasn't happened such as a slow air leak. The other advantage of TPMS is that after a few weeks use you will become familiar with the normal range of pressures for your RV and you will soon learn that you don't have to worry about minor inflation changes and don't need to be adjusting your inflation every travel day. I don't adjust my tires every travel day. In fact on a 7 week trip from Ohio to Oregon to Canada and back I only added 5 psi to one tire one time as it had slowly dropped down to only 1% above the minimum it needed to carry its load and the temperature had dropped by 60°F one morning.