Re: Tire Inflation
Reply #21 –
Dan, I would listen to wolf10. He has more knowledge and experience than any of us on this forum. He is extremely cautious before making a recommendation. We are not trying to criticize you or the advice you've been given. We just want you to question the advice you've been given, do more research, and make your own researched and educated choice. No problem sending me a personal message if you would rather discuss it that way.
As an example, to compare mine (97 U295 40') to yours (96 U295 36'), I load my rv heavy, near the axle limits rated by the FT plate at 10,500 front 19,500 rear. So off the Toyo chart, I use 105 in the front, 90 in the rear. This gives me a tire capacity of 10,740 in the front, 19,540 for the rear duals. Using your Uniroyle chart for your RS20 275x80x22.5, 90 lbs all the way around would give you 10,740 front capacity and 19,540 rear capacity respectively. Do you not see the error your tire store made, as wolf10 pointed out? You are 20 lbs overinflated all the way around from the maximum carrying capacity of your rv! I disagree with your tire dealer and agree with the Uniroyal tire inflation book.
Having been in the industry when rv mfgs, leading tire dealers, and rv dealers went to recommending the max inflation pressure printed on the sidewall, sometimes ignoring axle capacity, rv loaded weights, etc., they made steering sometimes horrible, and the ride sometimes horrible. I questioned the tire dealers, the service department, the supplier of tires to CC and Monaco, and the rv manufacturers Country Coach and Monaco. All responces came back to avoid lawsuits, after advice from their legal departments.
Note, this change in recommendations did not come from the engineering or service departments, but from the legal department.
In other words, I was told too often owners raise the weight they are carrying, they do not check the pressure before travel, etc. These three Industries wanted to avoid being involved in a suit involving underinflated tires.
After that I had a truck tire gauge in my desk as well as the correct tire manufacturers inflation guide. I had the good fortune to have a a free state run truck scale a few miles away.
To solve customer issues before, and after the sale, I'd visit these scales with the appropriate mfg tire inflation guide. Many an owner said they could not believe the difference. Telling them would not do it, it would take an hour and a half or two, the benefits were extreme.
If your trying to be cautious, and on the safe side, weigh each side of each axle when you are at full load, and then add 5 lbs of air for that little extra weight you might add. I carry two tire gauges that read the same, and a blown up copy of my Toyo inflation pressures.
As I said earlier; "I've attached the Uniroyal commercial tire inflation book. For 275-80-22.5, 110 lbs., that takes you to 22,750 on your rear axle, (check your plate, it is probably only 19,500) and 12,350 on the front axle, (which is probably only rated at 10,500). So it appears you are overinflated by 20 lbs. The pressure you've been recomended is too high, so I would at least weigh sometime when fully loaded and check with Uniroyal book for your tire size or at least do not overinflate beyond your axle capacity."
Both the Uniroyal and Michelin Guides recommend the same inflation pressure, 90 lbs, for your tire size, to get the above tire load capacities.
Topic: Tire Inflation