TPMS question

[Scott'n'Wendy]

I’m a fan of using the tire manufacturer’s load and inflation table for the weight the tire is carrying. I never go as low as they say is allowable, but I back off of “max cold.” I’ve blown quite a few tractor-trailer tires over the years inflating to max cold in the summer, but when I back off of that I seem to have better luck. This is anecdotal, of course. Our 310GK carries about 12k lbs on the axles, or 3k per tire. The left side is heavier, but I don’t know how much, so to be safe, I inflate to 105psi cold, or a little over 4k lbs per tire. The Grand Design sticker says 125psi cold, which is the max cold psi molded into the tire, so they took the worst case scenario of a per-tire loading of 4800lbs, or 19000lbs on the axles!!

Some would say if you overinflate for the load you are carrying, you will wear the center of the tire more than the outside, which does make sense. I will say after 20k miles, the Cooper Work tires on our 310 have a good flat profile.

I’d set the TPMS limits as others have suggested. And as always, YMMV, this is just what I do.

When you have 'G' tires I wouldn't think too many people would need them at 125

[Hoopy Frood]

I believe "G" rated tires are at their highest carrying capacity at 110 psi cold. I think the "H" rated tires go up to 125 psi.

[LMagelitz]

I believe "G" rated tires are at their highest carrying capacity at 110 psi cold. I think the "H" rated tires go up to 125 psi.

Yep mine are H. They are so stiff, I’m not sure they need air.

[jleonard]

You do understand that tire is engineered to be set at the max psi that is listed on the sidewall if needed and within that engineering of the tire, they are perfectly capable of going higher because of heating. It is basically not an acceptable practice to try and figure out where the tire is going to go and set the pressure lower, hoping that it will come up to the point that it should have been set to in the very beginning!

I completely understand the pressure settings. I also understand gauge accuracy and that is why I run if they read 70. Too many false alerts if set at 75 psi. I don't set the pressure low on purpose, but I run because I know how my trailer reacts. I also know that MY Tireminder reads a couple psi lower than I would get with my dial gauge. It has for the 2 years I have owned the TPMS.
I also am not anal about making sure the pressure is exactly 80 in the morning. I towed about 6500 miles last summer and never adjusted the pressure in my tires (GY Endurance). 8500 the previous summer.
And I also monitor temperature as well.

So long as your tires are capable of carrying the load your trailer puts on them when they are inflated to 70psi cold.

Yes they are capable. And they are wearing evenly after approximately 17 k miles.

[lorend]

We have just purchased the Tire Minder TPMS after suffering a flat tire and not realizing it. Ended up replacing two damaged tires. Les Schwab recommended 75psi not 80psi cold pressure. Should the Tire minder be set at 75 or 80 for alerts? We have a 2021 GD 2600RB.

Sorry to hear about the two damaged tires. I have been following Les Schwab advice for the last 40 years and have found them to be very good to deal with. A common misconception is that the max pressure stamped on the tire or on the side of your rv is a recommended pressure, but it is only a max pressure! It would be interesting to find how many people run their truck or even their cars at the max pressure stamped on the side of the tire. You would think that if they were running their rv tires at max pressure regardless of the load then the same logic would suggest that they are running their passenger cars at max pressure also. I just looked at my Elantra which has small tires and they are usually at 32 to 35 psi. The max pressure is 51psi. Wow, that would be a very rough ride. My truck tires run around 60psi when not towing and I raise them to about 73 to 75 for towing. I definitely do not run them at 80psi when not towing. Again, would be a very rough ride. In 40 years of driving semis I have had few tires go flat or blow. The only blowouts that I had were with high pressure and no load. Personal experience might have a lot to do with how I do things but 2.5 million miles of local semi driving should be worth something. We all have to make our own decisions and that does not make them right or wrong, as long as we are informed on the decisions.

[SGT ROC]

My personal preference (after a lot of research) is what's on the sidewall of the tires. And that is set when the tires are at ambient temp, on the morning of the trip, normally right around 70* ambient. In my case, tires say 80#, as does the sticker on the side of the trailer. I ran the original Westlakes (235 80R16's) the "E" rated China bombs everyone talks about, for 5 years. No issues other than a nail I picked up at a campground, and that didn't even show up till after a 2 hour trip on the way home. My TPMS showed under pressure the next day. As has been stated, under inflation is the biggest problem, as it creates excess heat. An absolute killer of tires over time. Next is ignoring the speed rating of the tire, also creates excess heat. LAST is weathering. I have found that weathering seems to affect some brands of tires more than others. My Westlakes were exposed to the sun om the road side most of the time while at home. I did not cover them but did use 303 on them a couple times a year. Again, no issues. I changed them because of age, not because of any defects. The tire manufactures put the inflation pressure on the tires for good reason. It's best to follow it.

[Hoopy Frood]

"The tire manufactures put the inflation pressure on the tires for good reason. It's best to follow it."

Yes, they do. It's to inform people what the MAXIMUM pressure is. Not RECOMMENDED pressure, but MAXIMUM pressure. They tell you the weight that the tire will support at its MAXIMUM pressure.

PS The caps are for emphasis, not to indicate shouting.

[SGT ROC]

"The tire manufactures put the inflation pressure on the tires for good reason. It's best to follow it."

Yes, they do. It's to inform people what the MAXIMUM pressure is. Not RECOMMENDED pressure, but MAXIMUM pressure. They tell you the weight that the tire will support at its MAXIMUM pressure.

PS The caps are for emphasis, not to indicate shouting.

One of my references is the attached site, but not the only reference I have used, just the one I saved several years ago "Max Tire Pressure". There is no good reason to not be at the Maximum Tire pressure. It does no harm. At the Max pressure listed on the tire it creates less sidewall deflection, which creates heat, which destroys tires. I guess the best thing is do what you feel comfortable with. What I have stated worked for me.

[Hoopy Frood]

One more riposte' and I shall let it lie. My thought would be they create tire inflation charts for a reason, and that reason would be to give the best ride for the weight. I have read some opinions, not necessarily mine, that say a lighter load, and max inflation pressure can be hard on the sidewall due to lack of deflection by the tire being "over inflated" for the weight it is carrying.

Just one of those things we'll have to agree to disagree about.

[ajg617]

I run what the RV/TV/auto manufacturers recommend. 125PSI in the Coopers, 60/80 in the RAM with or without trailer connected. Same on my cars. On my Coopers, it doesn't specify a maximum tire pressure - it specifies a maximum load at 125PSI. Per Cooper, my max tire pressure while running should be 20% over 125PSI or 150PSI. That's direct from Cooper. 132PSI is about as high as I've ever gotten in triple digits on the interstate.