Tire Pressure - An interesting observation

[Guest]

Having installed overrated tires on my rig and airing them back to my load, its doubtful I would experience the tread shedding that some have experienced. No disrespect but I'll keep my eyes on the road except when changing lanes. Driver distraction is a leading cause of accidents these days. Now throw in the latest style of infotainment screens (a disgrace IMO), its hard to not be distracted at times. You know there are potential issues when makers put the distracted driving clause on the screen on occasion that the driver must endorse.

Jim

[OurNewEra]

The Goodyear Endurance tires we have on our Imagine have stayed in an acceptable range all season without filling. They claim to have a special liner that holds air over a longer duration that seems to be true.

For long term storage that Rob has endured, it would be best to have them off the ground to avoid flat spotting. Otherwise, tires are supposed to be stored over winter at max air pressure.

Someday we will do the snowbird trip but need to stay close to my parents at this time.

Jim

I will second this. I recently switched from Westlakes to GY Endurance. I was always topping off the Westlakes. The GYs not so much. Actually only needed to add air once over the past 6k miles. I have to monitor when going from warm Florida to cooler northern locations.

[Beachcamper]

What drives me crazy while traveling is the different ambient temperatures affecting tire pressure. Airing up when air temps in the 80’s in one state then when I get to another state and it’s in the 50’s. When I check them before heading out they are no longer 80 psi but 75 psi. I have GY Endurance and they all seem to keep same psi across the 4.

[TheNescios]

Another reason I have not only a TPMS that helps me keep track of them, but also a Makita battery operated compressor. (think all the major brands are similar in quality)
It's a very fast and easy way to adjust tire pressure in the morning if the TPMS tells me there's a need to.
Who knows, maybe on my next trip I'll start a spreadsheet to track ambient air temp & tire pressures when I start out and then every few hours?
All of us "wannabe" engineers need something to think about when driving down the road!

[Jlawles2]

Guest I agree, sometimes there is just too much technology to keep drivers focused. Digital radio interface is nice b/c it makes tuning so much easier and faster than the older dial tuners.

Usually when traveling I have 1 or 2 "monitors" that check tire pressures on the TireLink system when the remote beeps. I look at tires when turning and am continuously looking in the mirrors for changes in the way the unit sits. The rear defroster lines make a great reference line for noting listing of the camper should a tire blow (Not on the Reflection, but have noticed it before).

[TheNescios]

Like the idea of the camera on the tires, but will need to see if something turns up on Craigslist or Offerup before I pursue the idea.
My oberservation of the influences of the sun & speed have been interesting from the standpoint of not knowing how much they affect things before I got the TPMS system.
The engineering side of my brain wants to understand the correlation of speed/sun/ambient temperature more to make up for my previous lack of understanding how interdependent they are.
Wonder if there's a way to have the TPMS send it's data to a computer so I can record the data and analyze it at a later date? (see what happens when a mind is left to wander?!)
Chris

[Guest]

Like the idea of the camera on the tires, but will need to see if something turns up on Craigslist or Offerup before I pursue the idea.
My oberservation of the influences of the sun & speed have been interesting from the standpoint of not knowing how much they affect things before I got the TPMS system.
The engineering side of my brain wants to understand the correlation of speed/sun/ambient temperature more to make up for my previous lack of understanding how interdependent they are.
Wonder if there's a way to have the TPMS send it's data to a computer so I can record the data and analyze it at a later date? (see what happens when a mind is left to wander?!)
Chris

Chris,

Goodyear has already performed this work when they developed their load tables for the GY Endurance line. Weigh at each wheel under worse case conditions and set the pressure. Or, some may feel more comfortable with a 5% increase over the inflation table to account for variation in the initial setting while cold.

I moved from a D rated Westlake that was posted on the side of the rig to be inflated cold at 65psi. I moved to E rated tires and set them at the same 65psi and do not have to mess with them all season since I can easily run down to 60psi or even lower based on the table. The GY Endurance tires also lose very little pressure over time.

To run this test, highly accurate measurements would need to be taken with lab grade temperature sensors in addition to lab grade pressure sensors such as from Kistler or AVL, PCB, etc.. Most likely, GY ran these tests on a test rig where load, pressure and sun load could be swept to pull in all the data. They most likely would have started at standard conditions and would have swept ambient (test cell) temperature, baro and possibly humidity. Tests could have been ran at max speed or speed may have been swept as well.
Once all the data is sorted, the table could be set based on the critical temperature when the materials begin to break down with the addition of a safety factor.
At least this is how I would have ran it.

Having stated that, if they used a reliable model to understand some constraints and boundary conditions, the experiment could have been paired down to save on cost.

Jim

[TedS]

auto tire psi.xls

FWIW
I created a spreadsheet for pressure/temperature.

[Jlawles2]

Cate&Rob Rob, It's taken my brain a while to catch up, but IIRC the acceptable pressure loss in a tire is 1psi or less per month moving or not.

[Cate&Rob]

Cate&Rob Rob, It's taken my brain a while to catch up, but IIRC the acceptable pressure loss in a tire is 1psi or less per month moving or not.

Hi Joseph,

I don't know if there is an "acceptable" level of pressure loss. I was just reporting what I observed across 12 months with the tires untouched but in the sun, out of the sun or under the trailer. All the same pressure loss. 1 psi per month does not seem unreasonable. Others have reported less pressure loss with another brand of tires.

Rob