Tire Pressure

[Overland]

I think the most likely answer is that your trailer probably runs slightly nose down. Even with the equalizer, that will put a bit more pressure on the front set of tires. I’ve noticed the same on mine, even though my trailer is only pitched down an inch or so, depending on what other load I have in the truck.

 

On mine, the temp difference is only about 5 degrees, and so I haven’t worried about it (though I’m actually doing some suspension modifications after the rally that should lift the rear of the truck a bit). The closer you get to the minimum pressure, or the bigger the temperature difference, the more important I think it would be to correct the problem, either by leveling the trailer (if that’s the issue), or compensating by running a different tire pressure on each axle. You also might make sure that you regularly rotate the tires front to back to give them equal wear.

 

Another thing to check for is that the shackles haven’t flipped on one of the axles, which can happen if the trailer has been lifted completely off the ground. That will put considerably more load on one axle and also bind the equalizer so that it can’t do its job.

[rideandfly]

Having a hell of a time figuring what preasure to run on Mich LTX M/S 2, LT225/75R16 Tires the Oliver came with . 80 psi Max. got that . Dry weight of Oliver being 4600lbs and gear 400lb including 20% water. I figure around 5000 total. any guesses?

 

 

Yukon,

 

For us and previous owners have run #75 Ollie's tire pressures at 50PSI. Our Ollie is equipped with BFG LT225/75R16 tires with maximum pressure of 80PSI. Could not find a load/inflation table for these tires, but did find another Michelin LT225/75R/16E load/inflation table a couple years ago to refer to. Tow Ollie with empty tanks ready to camp weighing in around 4950 pounds (Cat Scales) with creative loading of  Ollie & tow vehicle.

 

The tires are looking great after 30,000 miles and will probably look fine when we replace them in a couple years, too.

 

https://www.michelinrvtires.com/reference-materials/load-and-inflation-tables/#/

[Raspy]

Question: I run 55 psi in my tires. I have a TPMS system that monitors pressure and temperature. On my drive to Hohenwald and back, the two tires closest to the tow vehicle consistently ran 15 to 20 degrees higher temperatures versus the two tires towards the rear of the camper. The temps were never too high, just different. I assume there is a logical explanation for this. Any opinions?

 

Don,

 

Look at my post, a few posts back, that shows the actual measured weights at each tire and the tongue.  The rear axle is carrying more weight than the front one and my trailer is nearly perfectly level when towing.

 

This is puzzling because of the equalizer suspension system.  It seems to me that the axles must carry the same weight, but they don't.  If you are noticing a temp difference, it might be good practice to run the rear axle at 5 PSI higher than the front.  I check my tire temps at every stop and have not noticed any difference between the rears and the fronts.

 

I'm hoping to have some discussion about all of this at the rally.

 

Vector's experience is going to open this subject up and I want to carry it on so we can all be on the same page, and in agreement with Oliver.

 

See you at the rally.

 

John

[Overland]

I might also add that if you don’t have an internal TPMS sensor, whatever way you’re measuring the tire temperature is a bit of a kludge since what you want to know is the internal air temperature. Valve sensors, regardless how accurate they may be in themselves (I doubt very), will always show a lower temperature since the air in the valve stem is constantly being cooled by surrounding air. Getting the sidewall or tread temperature with an infrared thermometer is surely more accurate but arguably less relevant (outside of F1).

 

I’ve also read vastly different figures given as safe, everything from 250 degrees to the oddly specific 122.

 

So I think you have to take it all in context, not read too much into individual readings, and if some reading makes you nervous then just stop and check to ease your mind.  For what it’s worth, I don’t think my valve sensors have ever read anything over 95 or so and they certainly vary a good bit at times with no real indication as to why. Maybe other systems are better, but thats my experience. I always feel the sidewalls of the tires at fuel stops and heck if I could ever say if they’re anything but “warm”, and always less so than the truck’s tires, both front and rear.  Maybe there’s something important that can be inferred from that but I doubt it.

[KountryKamper]

Our Dill TPMS has internal mounted sensors and this is our 3rd Dill system on 3 different brand trailers. Our tire Temps usually run 25-30 degrees above the ambient air temperture. Most of the time on warm days they run in the mid 120's. I have seen them go to 130 on extremely hot and sunny days. The high temp warning on the Dill system is preset at 176 degrees.

 

Our Casita, Escape and Oliver have all run about the same tire temperatures with 3 differant Dill systems.

 

 

 

 

 

 

 

 

[Overland]

The Dill looks like a nice system.  I may have to switch to that when I replace my tires.  Do you ever have trouble getting a signal?  How is the battery life?

[KountryKamper]

It has its own small antenna and on our first system I did get some false alarms so installed the supplied antenna that is run under the vehicle and up into the cab. Having to mount the sensors, rebalance the wheels and run the antenna it is more work but a very nice system when installed although not for everybody because of the work involved. They say batteries are 5 plus years but I have never had one go dead.

[MrBig1]

I'm really glad I found this post. I've been running factory 80psi for a year now. Last year the bathroom door mirror broke. This year the power head came loose on the street side stabilizer. I don't have a TPMS installed yet so I'm going to drop to 60psi. I run a little heavy since I have my fresh water tank full before I hit the road. I have always made it a point to adjust my side mirrors so that I can see my trailer tires, check tire pressure each day cold and check tire temp with infrared handheld at fuel stops. When I change tires, I'll have a monitoring system installed.

[KountryKamper]

I dropped to 55 for our drive to the rally and one other small trip this year. I was going to try 50 on the return trip from the rally (190 Miles) but the 55 felt so good I am just going to leave it there for our trip out west. I could not tell any difference in tire temperatures between 60 and 55. Very smooth ride. At 55 the tires seem to have a good foot print and just a little buldge on the bottom sidewall. Our trailer weight is 5500 lbs.

 

[topgun2]

I too dropped my pressures to 55 for the 6 1/2 hour drive to the Owner's Rally.  No problems on the way west with a bit of rain - pressures stayed within a 10% gain from the cold setting.  But, on the way home with air temps approaching 90 and not a cloud in the sky, the pressures in all four tires came very close to the upper temperature limit I had programmed into the TPMS - a 20% gain.  Therefore, on my next trip I will increase the cold pressure to 60 in an effort to see if I can slightly decrease this temperature build-up.

 

Bill

 

p.s.  Both directions was mainly 4 lane/Interstate driving at 65mph.  Elite II with no water is about 5600 lbs.

[Overland]

Well I said I was going to try out 40 on the rally trip, but of course I forgot.  I'll save that experiment for another day.

 

I'm curious if percentage gain on pressures and temperature is more or less meaningful than the maximums reached.

[John E Davies]

I went from 45 to 42 psi and after 300 miles I think I will keep it there. I will check tire temps when I get a stinking hot day. So far the they are fine but the air is cool. I run full fresh tank and am around 6000 pounds, max.

 

John Davies

 

Spokane WA

[topgun2]

Just FYI - with every 10 degrees (F) change in air temperature, you can expect a 1 psi change in tire pressure.  Obviously, if the temperatures go up so will the tire pressure and if the temperatures go down a drop in psi can be expected.

 

After allowing for this fluctuating air temperature, any additional increase in air pressure above approximately 10% to 15% probably means that your "cold" starting pressure is too low.  On the other hand if a tire doesn't increase PSI within about 15 to 20 minutes of driving by approximately 10% to 12% probably means that your "cold" starting pressure is too high.  This is certainly not an exact science and depends on so many variables, but at least it is a place to start without simply totally relying on the seat of ones pants.

 

Bill

[John E Davies]

Keep the tires harder if you have no TPMS. Keep them harder if you travel a long way at high speed. Keep them harder if you have an Elite, which has a higher tire loading and may be more prone to instability than an Elite II (my opinion only). Increase pressure if your new lower pressure makes the trailer feel less stable. A large pressure change has much more effect as the number gets closer to the recommended minimum value. For example, a change from 80 to 60 is fine. But a change from 50 to 40 is not - work your way lower gradually! If you don’t want to bother with all this, set them at 55 or 60 and just check them every now and then.... IMHO.

 

The way they are delivered with 80 psi is simply way too high and it will just beat up your expensive trailer. FACT.

 

Interesting article. Scroll down for more of them from a company that really knows their stuff.

 

https://cdn2.hubspot.net/hub/210453/file-20229690-pdf/docs/importance_of_optimum_tyre_pressure_and_temperature.pdf

 

John Davies

 

Spokane WA