HOW TO: Tire Pressure Placard

[John E Davies]

Here is a load/ pressure chart I made using Michelin data. I plan to tape it to the inside of the closet door next to my Towing Checklist. Their info is published as a Flash page and it does not run well (or at all!) on some computers.

 

 

Attached is a Word Doc that you can print and laminate if you like, or just insert the whole page into your Owners Manual. printed at 100% it gives a 5 inch long placard.

 

Oliver-Michelin-Inflation-Tire-Chart-122017.docx

 

BTW I have suggested to Matt Duncan that this should become a new Tech Bulletin.

 

John Davies

 

Spokane WA

[BlaiddDrwg]

John.  I noticed in the other current thread on tire pressure that you said your tire pressure was at 60 PSI.  I may be confused but I thought the axles on the Oliver were rated at 3500 lbs.  So according to the table for psi, a max loaded trailer would be about 45 psi.  If I read the other thread currectly 80psi is the max, but appears to be way over what is recommended.

[John E Davies]

John. I noticed in the other current thread on tire pressure that you said your tire pressure was at 60 PSI. I may be confused but I thought the axles on the Oliver were rated at 3500 lbs. So according to the table for psi, a max loaded trailer would be about 45 psi. If I read the other thread currectly 80psi is the max, but appears to be way over what is recommended.

Actual load is more like 3150 lbs per axle (maxed out) on an Elite II, since some of the weight is carried by the TV, not the axles.  It's up to you to decide what works for you, everybody has an opinion. If you have trailer TPMS and watch it (not rely on the warning alarm), you can run lower pressures. But if you run over a nail and the tire starts to slowly deflate, a tire set at 45 psi will quickly get hot and give problems. A higher "starting pressure" gives a bigger time leeway, and more miles down the highway, when things do go wrong.

 

With tires set at 60, and your TPMS warning at 55, you have some driving time after you are alerted, before the tire is overloaded.

 

I would not hesitate to deflate to 35 psi on rough forest roads to reduce jarring, if I kept the speed below 30 mph....

 

The final factor is how hot are the tires? They will tell you when they are unhappy. Overloaded tires at highway speeds are HOT.

 

John Davies

 

Spokane WA

[Overland]

Most people won't be anywhere near 7,500lbs  though, and a few have even said they weigh in under 5,000.  I'd guess a lot of owners are in the 6,000lb range.  Per Michelin's charts, 35 or 40psi may be fine for many.  I think I set mine at 50 simply because I didn't have time to weigh it and I knew that pressure would cover me.  This trip, I'm planning time on the first day to visit a CAT scale.  I'll probably follow John's advice and run about 5psi higher than what Michelin recommends, at least until I have my tire pressure monitor set up.

[Raspy]

My Ollie weighs probably 5,500 lbs. when towing.  I run my tires at 60 PSI and I set them there when cold before we leave.  This is a good default pressure that will handle the trailer load just fine and keep the tires cool.  It still has some flex and is not rock hard like it would be a 80 PSI.  It also allows them to build pressure on hot desert highway runs where the asphalt might be at 140 degrees and the air at 100 or more.

 

I can tell the temperature difference in the tires even at 55 PSI.  They are warmer.  Every fuel or grocery stop, I go around and touch each tire.  They are always the same temp, if inflated the same, and they are just slightly above ambient air temperature.  On the road, I don't use a gauge, I just touch each one and compare the felt temps.  Every time you use a gauge you let some air out and run the risk of the valve leaking.  It's not necessary to use a gauge when stopping for fuel, just use temperature.

 

Warmer tires are under more stress and they make the trailer harder to tow.   This is why I would never run them at 45 psi, for instance, even if the chart said they could handle the load at that pressure.  The chart is more a minimum guide than a definite number that you must follow.  And as John mentioned, you have no head room at the lower pressure in the event of a slow leak.

 

Off road, or on secondary gravel roads, it's a different matter.  I'm talking about droning down the highway at speed.  That is when the higher pressure is a good policy.  On back roads, it's a good idea to air down and travel slowly, but you have to factor in the difficulty of airing back up.  This applies to the truck too as I like to air it down on rough roads or in the snow.  When going into Death Valley I'm on gravel, or worse, for a hundred miles or more and when I come out, I can get back to town with limited speed on paved roads to air back up.  I have a compressor, but it's for emergency use as it's not real easy to use.  If we are only going five miles on a rough road, I'll just go slow and keep the pressure up.  This is what we did at Sun Valley for the Eclipse.  Just idled along for a few miles on a rocky road as we climbed to our spot out in the forest, then idled back out.  No need to hurry in that situation.

[Mainiac]

An infrared thermometer from Harbor Freight is real cheap these days. Flash it at a tire and done. But, on the plus side you can quickly check wheel bearings too. Try that with a bare hand on a faulted bearing and your troubles will be compounded quickly...

 

 

[Raspy]

You can't get hurt by quickly touching the center caps on the wheels, but they aren't a very good measure of problems either.  The infrared thermometer can look at the brake drums though.  A failing bearing is likely to make the drum hotter and it will also develop play that you can find by grabbing the top of the tire and then pulling and pushing on it to look for play.  This is a good thing to do at the campsite in the morning.

[Corcomi]

I noticed today that the tire placard on the Oliver says that the recommended tire pressure is 80 psi. Now when I took delivery last month Rich told me to keep it at 60 psi as the averaged weight of the Oliver is about 5000 lbs. with “stuff”

 

so add that to the thread...????

[ScubaRx]

...the averaged weight of the Oliver is about 5000 lbs. with “stuff”...

 

At only 5000 lbs that sure doesn’t seem like much stuff. With an advertised dry weight for the Elite II of 4600 lbs, a full tank of water and propane will get you most of the way to that. I’d expect 6000 lbs to be more likely. Ours is north of 7000.

[John E Davies]

Don’t forget the cast iron cookwear, firearms and ammo ..... they are pretty darned hefty.

 

I haven’t bothered going to truck scales, but I am guessing that, for Mouse, 6ooo lbs is a typical towing weight. I actually try to keep the weight down, other than a full fresh tank always....

 

The folks that live months at a time in their trailers carry a LOT more stuff than those of use who take short trips.

 

Merry Christmas.

 

John Davies

 

Spokane WA

[Overland]

Corcomi wrote:

…the averaged weight of the Oliver is about 5000 lbs. with “stuff”…

At only 5000 lbs that sure doesn’t seem like much stuff. With an advertised dry weight for the Elite II of 4600 lbs, a full tank of water and propane will get you most of the way to that. I’d expect 6000 lbs to be more likely. Ours is north of 7000.

Ours was 5,565 from the factory.  With 'stuff' I'm sure we're well over 6.  I imagine ours is one of the heavier ones, though.  Bigger axles, extra solar, etc.

[John E Davies]

Update to an old thread. I am now running 42 psi which seems a decent compromise between tire temperature, tread wear and cushioning. I do notice a negative effect on fuel economy when they are not rock hard. Coincidentally, that value is the exact same as in my Land Cruiser LT 10 ply tires. The truck and trailer weigh about the same and that makes it easy for me to remember ....

If you don’t have TPMS in your Ollie, run a higher pressure for a better safety margin.

John Davies

Spokane WA

Edited September 25, 2020 by John E Davies

[Galway Girl]

I think this is the raw data used for making the Table John Posted at the start of this thread about 2 years ago. *the data seems to match from 40 PSI up...

Just putting it here in case the original data set get's lost as those tires are no longer put on Olivers...nor appear to be mfg in Canada.

 

Edited November 2, 2020 by ctshort09

[Ray and Susan Huff]

18 hours ago, ctshort09 said:

I think this is the raw data used for making the Table John Posted at the start of this thread about 2 years ago. *the data seems to match from 40 PSI up...

Just putting it here in case the original data set get's lost as those tires are no longer put on Olivers...nor appear to be mfg in Canada.

 

From my re: "Oilver installs Cooper E rated 10-ply nitrogen fill tires. The size is 225/75/R16."  Didn't give me specific tire name.

 

 

[John E Davies]

FYI, with the same size tire, and the same load rating (10 sidewall plies, Load E), you can use the old chart, no worries. If there are any differences in recommended pressures between tire manufacturers, they would be so small as to be negligible. You should use tire operating temperature (and tread wear over the very long term) as an indicator and adjust air pressure as needed. And if your interior is showing signs of distress (utensils and dishes thrown around) then lower your pressure a bunch.... or don't drive so fast over speed bumps. 😉

Try 50 psi, lower them gradually from that to where the tires seem to be 'happy'.

John Davies

Spokane WA

[Jim_Oker]

FYI, the tires on a December delivery model are a Cooper DIscoverer HT3 LT225/75R16

[John E Davies]

4 hours ago, Jim_Oker said:

FYI, the tires on a December delivery model are a Cooper DIscoverer HT3 LT225/75R16

Are they still Load E (10 ply)? I am not sure why they choose that stiff of a tire on these trailers, Load D would be plenty adequate , would weigh less and would also make the ride a little softer. Tho the heavier tires will resist sidewall cuts a little better.

John Davies

Spokane WA

Edited January 3, 2021 by John E Davies

[Jim_Oker]

51 minutes ago, John E Davies said:

Are they still Load E (10 ply)?

Yes they are in this size, looks like your inflation placard works for these as well (at least based on my limited understanding). Cooper Discoverer HT3 Commercial Vehicle Tire | Cooper Tire

 

[Jim_Oker]

I imagine trailer sidewalls on average take more abuse than car/truck sidewalls.

[Nimrod]

This is a good thread on tires, load and air pressure. Thanks for posting links and data.  Some time has passed since the confirmations on the Cooper Load Range E tire.  If anyone knows that those specs have changed please chime in.  Otherwise I’ll assume those are the ones being installed on the new hulls. 

Rod 

No Hull Yet. 😉