I want to start a new thread about nothing, and let it run...

[Beau388]

Tires heat because of tire flex. You can check the by stretching a rubber band repeatedly, The tire is flat where it touches the pavement and round every were else. Well that is not strictly true. Depending on internal air pressure and tire design, the tire will develop a secondary, rebound flex wave about 20 degrees after the tire looses contact with pavement 40 to 100 mph. (That is why 12 inch trailer wear out in about 2,000 miles at speed of 60 mph). The temperature of the pavement also figures in to the pressure gain; as does, the atmospheric temperature and the sun shine. But, the primary factors are: tire diameter, weight on the tire and air pressure. These factors determine the amount of tire flex and the frequency.

Thus, there is no pressure gain statistics; only empirical knowledge. Tire manufactures specify max cold inflation pressure, max speed; as well as: tread wear, traction and temperature grades. So asking what is normal tire pressure gain unless someone has a coach identical to yours with the same tires driving the same speeds in the same conditions.

For me, with 18,000 lb coach, shod with 6 Sumitomo ST719 tires, cold pressure of 75 psi on the front and 90 psi on the rear: on a 100 degree sunny day, on a black pavement: 89 psi on the front, inside duals 115 psi and outside duals 110 psi. Front axle is carrying 5,040 lbs and the rear 11,880 lbs towing 3,100 lbs with the towed tire pressure at the max cold pressure (50 psi on the dolly and 44 psi on the truck's rear).

 

[dkoldman]

Left home with (new last year) Agilis tires all inflated to 80 psi (temps low 70s°) on the motorhome... Jeep (towed) tires @ 33 psi. After about 1.5 hours driving on freeway I got an over pressure TPMS alarm... rear inners were 97# & 98#. Fronts were about 90. Jeep tires were barely warm at 35#.

Last year I recall all the motorhome tires increasing about 10# to around 90ish... but this was a little excessive.

Thoughts? Think I should start with lower pressure? Leave it alone... no worries??

For reference, all my tires are always set at 82 cold.

My Tire Patrol was set to alarm at 106 because that is the temperature I never saw even when driving in excess Texas heat. So industrial engineering process controls says that is would beyond 3 sigma of standard deviation. If I ever hit that it would be some special cause because I believe 104 was the max I ever saw on any tire.

With that said, I replace the Goodyears in theory cheapo China made Goodrides. Higher rated tires. They run a lot cooler, I still drive the same way. I lowered the Tire Patrol Alarm to 100F but it is yet to trigger. I could prolly set it lower again, but I don't care if the tires are 100 or less.

Sometimes, I can actually see temp differences on the side of the RV that is in sun. It goes back and forth for me on whether the inside dually is hotter than it's outside counterpart.

 

[ducksface]

I have been known to lower my pressure when the pavement is too hot.
I'm not sure why I shouldn't.

To do this I just have to know how much it drops when cold again in the morning and not go below my head-gamed, psuedo-science, threshold.
There are things to consider such as the density of cold vs hot air vs a pothole vs my rim being bent...

These are the things I think about when driving.
My thoughts are almost always with the vehicle and how assembly costs compromise any vehicles potential and how i can mod my way around the simpleton nature of a vehicle's manual's instruction or the rubber sway bar mounts they save three dollars on vs pouring my own urethane mounts.

There's more butt covering by 600% then there is science in those numbers that manuals talk about.

But:
If you won't experiment or won't think outside some imaginary box you've built for yourself do not mess with tire pressure.

There are many things I don't want to learn or know so I just do as I'm told.
Some things, entirely personality and professionally and time based, just aren't worth knowing, learning or experimenting with.

My rain collection or Javelina problems have no bearing on urban folk. There is no need to learn about them for 99.999% of people.
Just leaving the tires alone is fine. 99.999% of people shouldn't begin to care let alone need to learn.

The above is just a preemptive strike against the
" my manual says" that is inevitable.

 

[ducksface]

Generally:
What do you think about when driving?
I'm not a music guy so the radio is all but never on.

We know for sure some are not thinking of traffic when driving.

What is your standard
Go to
Group of things?

Outside of being five cars ahead of myself in traffic flow,
Mine are all but always mods.
Whether it's the vehicle or tree wells or gates or whatever.

 

[JeffThor325]

Generally:
What do you think about when driving?
I'm not a music guy so the radio is all but never on.

We know for sure some are not thinking of traffic when driving.

What is your standard
Go to
Group of things?

Outside of being five cars ahead of myself in traffic flow,
Mine are all but always mods.
Whether it's the vehicle or tree wells or gates or whatever.

Funny enough, I'm also a non radio listener (since 2003). I tend to think about a wide range of things but when driving is definitely where I get most of my biggest breakthrough ideas.

 

[Chateau_Nomad]

I sure wouldn't lower the pressure
What is the max inflation on the tires?

Just arrived home. I "torqued" my lower back, so I'm icing it trying to relieve pain. I lowered the rear tires to 78# last evening. The rears averaged 89# - 90# on the drive home. No alarms. Seems as though the max inflation was 80... that's what I have the TPMS set at. When I get the back pain under control I'll go check the sidewall again.

These tires have a more aggressive tread than the original Dynapros. Could be why they run slightly hotter??

 

[MLP-THOR]

Just arrived home. I "torqued" my lower back, so I'm icing it trying to relieve pain. I lowered the rear tires to 78# last evening. The rears averaged 89# - 90# on the drive home. No alarms. Seems as though the max inflation was 80... that's what I have the TPMS set at. When I get the back pain under control I'll go check the sidewall again.

These tires have a more aggressive tread than the original Dynapros. Could be why they run slightly hotter??

Use your phone and take a picture of the tire. Easier to enlarge it on the phone and read the information. Save your back.

 

[Chateau_Nomad]

Even with all 4 at 78# the inner driver side always ran higher by 1#... which pressure wise to me is immaterial.

I haven't got a Cat scale weight since the new tires, so that's on the agenda. Also some load shifting and balancing is in order. Could be a factor in the why they're running hotter.

Speaking of thinking of things, this is the crap I DON'T want to think about! I want to know the load rating of the tires, exact 4 corner rig weight, correct cold tire pressure... basically the stuff Beau alluded to above.

Then set the TPMS appropriately so I DON'T have to think about it unless the TPMS tells me. But to correctly set the TPMS I need to find out what is the maximum SAFE increase in tire pressure from the baseline cold pressure based on my situation. Currently I don't know what that is... so setting the TPMS to alarm at say, 100# seems arbitrary and random. If I found text from the manufacturer saying it's no big deal for a 30# increase in pressure due to heat... no worries. But ... ???

 

[ducksface]

I thought every tire I've ever bought has a max pressure embossed on it.
I'll have to look.
My atv type tires have nominal pressure and seating pressure on them.

 

[16ACE27]

Just arrived home. I "torqued" my lower back, so I'm icing it trying to relieve pain. I lowered the rear tires to 78# last evening. The rears averaged 89# - 90# on the drive home. No alarms. Seems as though the max inflation was 80... that's what I have the TPMS set at. When I get the back pain under control I'll go check the sidewall again.

These tires have a more aggressive tread than the original Dynapros. Could be why they run slightly hotter??

Yep. And the sidewall max pressure is COLD PRESSURE, not hot running pressure.

 

[MCP-THOR]

My rain collection or Javelina problems have no bearing on urban folk. There is no need to learn about them for 99.999% of people.
Just leaving the tires alone is fine. 99.999% of people shouldn't begin to care let alone need to learn.

The above is just a preemptive strike against the
" my manual says" that is inevitable.

Do you have a Javelina manual? I could use one. (And not the AMC Javelin manual).

 

[lwmcguire]

Just arrived home. I "torqued" my lower back, so I'm icing it trying to relieve pain. I lowered the rear tires to 78# last evening. The rears averaged 89# - 90# on the drive home. No alarms. Seems as though the max inflation was 80... that's what I have the TPMS set at. When I get the back pain under control I'll go check the sidewall again.

These tires have a more aggressive tread than the original Dynapros. Could be why they run slightly hotter??

We had a significant amount of tires on various equipment for many years. The highest temp increases i ever noted was when we went to heavier ply tires, they don't dissipate heat as fast, and tires that were softer sidewalls even at the same ply rating. As Beau noted it is flex and load for the most part that generates heat. I always run on the higher side of psig due to the past of always having the hot tires blow out in high temps. The fix/cure for the higher ply tires was higher operating psig for the load. And we didn't let air out when running empty or not towing.

 

[Chateau_Nomad]

I know last season I was right on the edge of GVWR. The sane thing for me to do is load the rig "road ready" and hit the CAT scale. Then consult the Michelin charts. Based on that... make a decision and move on!

 

[ducksface]

Only two neighbors called me today.
One had a flat tire and wanted me to show her how to use the compressor.
She had the the quick coupler taped to the tire valve stem. No air chuck, just the quick coupler.

Wouldn't hold air(I brought my ryobi compressor) and one lug nut was so tight I had a big four way and a six foot rock bar as an extension and I twisted up the four way...but it's stuck.
So, too early tomorrow morning I'll air her up, allowing her to town and I'll use the favor I called in at the tire shop so she can get fixed.

 

[ducksface]

I finally pulled the winch from out behind the front bumper on the zr2.
What I thought would be the damn fuse able link that had left me frame deep in a wet water spring, was really a fully locked up motor.

So I pulled a spare 12,000lb winch from the shed.
I'll now have a 12,000lb winch where an 8000lb winch was, on a 6000lb vehicle.
If it fits.
I may have to mod the mod so this mod will fit.

 

[ducksface]

Do you have a Javelina manual? I could use one. (And not the AMC Javelin manual).

Nor any more.
But I did own a 71 sst 401 4sp.
It's like an amx but with drum brakes.
Cost was MORE to delete the radio and heater and disc brakes than to have them.

Only 40+ made. Amc drag race special orders.
More rare than a zl1 camaro.


No value because squirrel-boys always want a camaro(we've owned dozens of 1st gen f bodies)
I chased that particular singular sst for 40 years.
Finally caught it and wasn't worth restoring. Sold it.
Dream realized, loss cut.

 

[MCP-THOR]

Nor any more.
But I did own a 71 sst 401 4sp.
It's like an amx but with drum brakes.
Cost was MORE to delete the radio and heater and disc brakes than to have them.

Only 40+ made. Amc drag race special orders.
More rare than a zl1 camaro.


No value because squirrel-boys always want a camaro(we've owned dozens of 1st gen f bodies)
I chased that particular singular sst for 40 years.
Finally caught it and wasn't worth restoring. Sold it.
Dream realized, loss cut.

My feeble attempt at humor didn't get very far. This is the model I was referring to. Nasty, disruptive cacti eating guys!

 

[ducksface]

No, I got it.
It's just that some things need to lay were they were found.

(And mine is indeed a pig problem. Four big adults have replaced our normal couple and their yearly baby)

 

[ducksface]

We did.

And zero on the medications.

We're not on any pills, and the programs just seemed to make you pay your deductible as a monthly fee. We couldn't figure out any advantages other than someone paying $100 monthly because they'll never have $1200 cash at any one time.

Was the only thing that made sense.

Now, if we lived in the deepest, darkest urban areas and never left, then the cheap ones make some sense.

RV people do not squat themselves in downtown Detroit and never leave.

Think twice; don't cry.

My spousal unit had her gallbladder taken out a month ago.

We paid $6 for pain pills she didn't use. Not a single penny more for anything. No co-pay.

The guy who did it rotates from behind the 7-Eleven to a vacant field throughout the week. Catch as catch can...no appointments needed.

 

[ducksface]

See the post above for context:

My spousal unit had her gallbladder taken out a month ago.

We paid $6 for pain pills she didn't use. Not a single penny more for anything. No co-pay. plan G.

Sister in law is on a in-house plan of some sort and can't get a simple knee scrape paid for.

The guy who did the bladder surgery rotates from behind the 7-Eleven to a vacant field throughout the week. Catch as catch can...no appointments needed. Bring something sharp.