Tire pressure increase during towing.

[markdoane]

Stan, if your cold tire pressure is measured at 50F, then the tire temperature that corresponds to 77 psi is 130F.

I have a single axle with about 2400lbs per tire, and I usually see a 10 psi increase from cold morning to 65 MPH in the afternoon. I think your pressure increase is a little higher than I would like to see. I'd check to see if you have a tight bearing or a draggy brake.

[Stan Drury]

Barts, I think that you said keep the tire temperature below 160 - 170 degrees.
Maybe I should get a temp meter to go with the pressure gage.

[barts]

One of the those $20 infrared gizmos comes in hand for evaluating tire & hub temps.

- Bart

[eldin]

my tire gauge reads 50 psi on maxis M8008 radial (steel belted) ST225/75R15. 25ft AS Excella. Tire decal says max PSI inflation 80PSI. Person I bought TT from says 60 PSI inflation. HELP. Live in NC summer heat Eldin 89 AS Excella 25 ft.

[golddigger]

I have pressure and temperature sensors in my truck and trailer tires. The sensors are mounted on giant hose clamps on the inside rims, so you do not see them from the outside. The temperature varies greatly, and affects the pressure. The pressure that you mentioned sounds a bit high. I can get into the mid 70s on the rear tires of my 2500HD when I tow my 31ft. When my trailer tires reach 73 or so I start to worry, unless all four are showing the same thing.

Typically, I see a tire temperature of 35F above ambient. On a hot day this can definitely climb up there. Is the pavement new? Really black pavement is hotter than concrete, for example. The sunny side of the trailer is often up by 10 degrees. When it rains, it can bring down the tire temperature 20-30 degrees in a matter of a few miles. Speed brings up the temperature, of course. I often stay around 65MPH.

Temperature is often a better leading indicator of a problem than pressure. If one tire has a higher temperature than the others it is typically a sign of a mechanical problem, such as bearings, brakes dragging or a structural problem with a tire that is a few hundred miles away from popping.

[Protagonist]

Originally Posted by eldin

my tire gauge reads 50 psi on maxis M8008 radial (steel belted) ST225/75R15. 25ft AS Excella. Tire decal says max PSI inflation 80PSI. Person I bought TT from says 60 PSI inflation. HELP. Live in NC summer heat Eldin 89 AS Excella 25 ft.

Simple answer, go with what the trailer's owner's manual says for tire pressure. If you don't have and can't get the manual, then you can take the previous owner's word for it.

As long as that number is lower than the maximum pressure listed on the tires, anyway. Never exceed the pressure listed on the tires.

[AirsDream]

Originally Posted by golddigger

If one tire has a higher temperature than the others it is typically a sign of a mechanical problem, such as bearings, brakes dragging or a structural problem with a tire that is a few hundred miles away from popping.

Well, maybe, sometimes. I monitor my tire and hub temps at EVERY stop. The right rear tire on my tow vehicle ('08 GMC 2500/Duramax/Allison) always runs about ten to twelve degrees higher than any other tire on the truck. It has done that since the truck was new. Has done so for 60,000+ miles. Tire rotation doesn't solve it. Meticulous tire pressure checking (plus the TPMS readout) tell me it's not cold pressure related. And (I check, as mentioned), it's not hub / bearing temperature, either. And though I haven't scaled the truck and trailer from side to side, I load pretty carefully, so that the loads are very similar left to right. It's also not brake drag - the pads look identical left to right, and if they were dragging, I'd get hub temperature increase. First time I discovered it, I thought it was sun side / shade side differences. Not so.

Only thing I can think of is that since due to road crown, this is the "low" side of the truck, there is some weight transfer to that side, and since the rear tires carry more of the load, the right rear gets most of the low side "extra loading" and so more hysteresis effects from sidewall flex, etc. - outside of that, it's a mystery.

But it's not a tire with a structural problem that's about to pop.

BTW, the day I bought the truck, the salesman told me he'd seen a lot of them with this OEM tire (Bridgestone Duravis), and that "I'd really like them." ... of course, I thought that was a bunch of salesman malarkey, but at least insofar as durability is concerned, he wasn't fooling. I measured my tread depth earlier this week, and at 60,xxx miles, they still have half of their tread depth remaining ... and have always seemed to have reasonable wet and dry traction and also do o.k. in deep snow.

[azflycaster]

The problem is that the owners manual was written for the original tires and the tires on the trailer could be a different rating.

[AirsDream]

Originally Posted by eldin

my tire gauge reads 50 psi on maxis M8008 radial (steel belted) ST225/75R15. 25ft AS Excella. Tire decal says max PSI inflation 80PSI. Person I bought TT from says 60 PSI inflation. HELP. Live in NC summer heat Eldin 89 AS Excella 25 ft.

If you go here: http://www.maxxis.com/Repository/Files/m8008load.pdf
you will find the Maxxis inflation chart for your tires.

If the tires say they are max. inflation 80 psi, that leads to conclusion that they are load range E tires. At 80 psi, they'll carry 2,830 lbs. EACH - I didn't look up what your trailer weighs, but GVW for it has to be WAY below 11,320 lbs. (2,830 * 4). Thus, at 80 psi inflation, you won't tend to get overheat blowouts, but your trailer is gonna' take a pounding.

If it were my trailer, I'd either a.) call Airstream for a recommended inflation pressure with those tires, or b.) back the pressure down a bit, more in line with the load they're being asked to carry and see how the tread wears and whether the trailer is starting to suffer damage.

[Gene]

Originally Posted by eldin

my tire gauge reads 50 psi on maxis M8008 radial (steel belted) ST225/75R15. 25ft AS Excella. Tire decal says max PSI inflation 80PSI. Person I bought TT from says 60 PSI inflation. HELP. Live in NC summer heat Eldin 89 AS Excella 25 ft.

Eldin, the 80 psi maximum ratings means you have Load Range E tires (used to be called 10 ply). Tire pressure should be enough to carry the weight each tire supports. Too much pressure for the weight will result in wearing the center of the tire tread faster than the sides. Too little will wear the sides of the tread faster. There are tread depth gauges available to measure this for around $10.

There are tables on various websites (Tire Rack is one) that tell you how much weight each tire supports for a given pressure. You can find on the weight of the trailer in a couple of places on newer trailers—often on the inside of a wardrobe door and on a plate on the lower side of the trailer—near the front. Some tire store chains have info on their websites too.

Or call the tire manufacturer to get recommendations for how much pressure each tire should have. Have the loaded weight (GVWR) of the trailer and exact name and dimensions of the tire ready. Don't be surprised if they aren't sure either.

You will get recommendations to have from 50 to 80 lbs. in the tires from various Forum members. Tire pressure is debated frequently on this Forum.

I think the tire tread depth tells you whether what you have been doing is working, but doing the research on weight vs. tire pressure helps you make a decision beforehand.

Tire pressure is different for every tire and every trailer combination.

Gene