"LT" tire pressures on Expedition

CapriRacer wrote:
One of the reasons I love following these threads - even though I don't own a travel trailer - is posts like the one below:

falconbrother wrote:
I read whats on the tire and do that. My rule is: Do not exceed the manufacturer's specifications. People try to outsmart the engineer who designed things. I do what the engineer said do.

That's contradictory.

The engineer (That would be me!) says what is on the sidewall isn't a recommendation - that reading the sidewall isn't going to give you the answer.

And if you read my post further upstream correctly, you'll notice I didn't actually give a recommendation. I merely asked for additional information and made a statement about the relationship between P type tires and LT type tires.

What you say makes a lot of sense to me as an engineer (though not a tire engineer). I would like to add that the rating on the side is a MAXIMUM pressure and a Maximum load so they need to be read in that context. Likewise, most wheels have a maximum pressure rating. If yours don't I would assume that it is no more than maximum pressure rating of the original tire. While I agree that wheels rarely fail I feel that there is a good reason behind the ratings.

One of the things that I believe causes confusion among consumers is that tire pressure vs weight capacity charts don't seem to be available for the tires we use. I can easily get them for the load range H tires on my motorhome but not for my pickup or any car. A while back I put high fuel economy tires on a Taurus and noticed that they were rated at 50psi instead of the 35psi on the original tires. That raised the questions in my mind of whether I had to use the higher pressure to get the advertised fuel economy benefits and were the wheels rated for it. I called customer service at Goodyear and they flat out refused to answer any questions and would only tell be to use the recommendations on the manufacture's sticker. They also refused to discuss the pressure ratings of any specific tire but the did finally give me excerpts from a chart developed by that American Society of Automotive Engineers from who knows how many years ago. When I pointed out that the chart had a lot lower pressure rating than the sidewall did for the fuel efficient tires at max load they said that going up to 10psi over was not a problem.

Anyway, if you can help us find some data developed by engineers and testing instead of going by opinions I would appreciate it.