The continuing saga of tire pressure...

My logic is to get the MH weighted and inflate the tires to the pressure the tire manufacture recommends. Has worked for me for 11 years and 80,000 miles.

I have always ran back @ 100 psi and front @ 100-105 psi. Never weighed the coach. Change the tires @6K mi. Last yr I bought a TPMS system and notice they read from 92 psi cold to 110 psi hot. Never

Tire and alignment shop that I use inflates to the pressures I tell them. They ask me. The maximum needed is also posted in the door jamb.

But the Honda dealer where I take my towed vehicle about once a year always overinflates, to maximum for the tire, although appropriate pressures are in the door jamb. I think they are assuming the tires will not be checked again until the car next comes to them for service, the TPMS complains, or one of them goes flat. For most of their customers, it isa fairly safe assumption. Gasoline filling stations stopped doing this for customers about 60 years ago.

I am not going to tell you how I check my tiers or what air pressure I use. I will say I am not like the gentleman camped next to me last week who saw me doing my "magical" test of tier pressure. He told me I was wasting my time as he had the dealer check his tiers in the spring each year and there was no need to waste time doing it in between. Well all I could do is say GOOD LUCK.
Bill

goufgators wrote:
My coach has been weighed and according to the tire manufacturer's PSI chart, I should be carrying 80 psi. But, when you (or I) have new tires installed, the tire company insists on pressuring up to the psi identified on the sidewall. Why is that? Do they consider it a liability issue if they put in a lesser amount of pressure as requested by the buyer? It's not a problem since, when I arrive home, I can then adjust the psi to whatever I want. But, just wondering why the dealer won't agree to a psi less than the sidewall amount. Any thoughts?

Whatever the case, if my chart called for 80psi, I'd be running at least 90psi for taking care of the many variables and especially with leaving on an extended trip from a warmer climate.

Effy wrote:
I find some of this - well maybe a lot of this - pretty silly.

It's just human nature.

Pretty much EVERYBODY thinks that they are a genius and everybody else is ignorant or stupid.

The truth IS that half of the people in the world are below average.

DrewE wrote:
(It's also somewhat exacerbated by the somewhat basic and unrefined front suspension design of the Ford E-series chassis.)

And improper alignment for the application......which can be fixed.

I find some of this - well maybe a lot of this - pretty silly. If you think that + or - 5 psi will change the traction of a 20 - 40k lb mh amounting to anything of significance you need to re-think. That happens on it's own in few minutes based on the direction of the sun. I swear some folks on here make things waaaay too complicated or just like to argue or both. EVERY single time it turns out to be 5 pages of arguments. EVERY time. Some folks on here need a snickers.

Since 4+ gives more "bite", the extra 5 I add to the weight charts must be perfect. Actually I go 5 over because of the weight shift that a strong crosswind can put on the down wind tires. Comparing a car tire test to a MH/truck tire is of dubious value for the amount of bite.

Kayteg1 wrote:

DrewE wrote:

Kayteg1 wrote:
Beside lower ride comfort, what is wrong with inflating the tire to max sidewall pressure?
When was the last time you have seen semi-truck drivers dropping the tire pressure after dropping off the load?

Overinflation causes reduced traction, which can mean compromised handling in an emergency situation.

Do you have a real test to confirm this theory?
Edit. Found test done by Edmunds.

actually improves handling because it provides more "bite"

That test found nothing of the sort; in fact, they didn't actually test overinflating the tires at all, so far as I could tell. It merely found an expert who claimed that a slight overinflation improved handling slightly but compromised braking slightly. Perhaps the expert was correct, at least for some classes of vehicles or some recommend inflation pressures, and perhaps the expert was mistaken (or overgeneralizing)—I do not know. Nowhere did this expert recommend a substantial overinflation.

I remember seeing some informal but reasonably scientific tests performed by a car enthusiast at a skid pad with various tire pressures, and found that for their car the manufacturer recommended pressures provided the greatest lateral grip. I cannot now find exactly where I saw that. However, it would be a fairly simple test to replicate if one were so inclined. (I don't really recommend taking a class A motorhome for trials around a skid pad, though.)

On Ford-based class C motorhomes, at least, overinflating particularly the front tires can lead to quite squirrelly handling, and reducing the pressure to the correct value for the weight often greatly improves that. This is not exactly a traction-related issue, since the handling problems are not due to losing traction, but it is a control and safety issue. (It's also somewhat exacerbated by the somewhat basic and unrefined front suspension design of the Ford E-series chassis.)