Community Forums

Tergeo · 11-15-2022, 09:28 AM

We recently had work done on our 1500 RAM. The techs decreased my tire psi to 45 even though I have speciality tires that state the psi is 80 cold. The tech told me that I will wear down my tires faster, and they do not need to be inflated to the full psi even though I am hauling approx 7500 lbs with our TT. So my question: Do you follow the recommended psi on your tires, or under inflate for better breaking and tire wear? This sounds unsafe to me.

Suburbazine · 11-15-2022, 09:42 AM

A 1500 has no business being filled to 80psi. The max cold fill on the tire is not the number you fill to, it is the maximum allowable payload pressure (3500lb capacity @ 80psi). Give me the make and model of your tires, expected weight over axle (A CAT Scale visit is like $11) and I'll give you an exact number. Running that high of a pressure on an underloaded axle will absolutely cause the tire to crown wear and make the ride unnecessarily rough.

There's no way you can load a 1500 axle to require 80psi in the tire, without the truck being illegally overloaded. Even the 2500 RAM only needs 65psi in the tires to meet payload capacity. A RAM 1500 has a MAX GVWR of about 7100lbs... or roughly 1800lbs payload capacity. Your over axle weight is probably a close split 4k rear 3k front. Any of the 80psi tires are rated to handle 3500lbs per tire. Since you can't possibly put the entire GVWR on the rear axle, you can't possibly need the tires set anywhere close to 80psi.

BayRunner · 11-15-2022, 09:44 AM

Quote:

Originally Posted by Tergeo

We recently had work done on our 1500 RAM. The techs decreased my tire psi to 45 even though I have speciality tires that state the psi is 80 cold. The tech told me that I will wear down my tires faster, and they do not need to be inflated to the full psi even though I am hauling approx 7500 lbs with our TT. So my question: Do you follow the recommended psi on your tires, or under inflate for better breaking and tire wear? This sounds unsafe to me.

As the tech mentioned, just because the tire reads it can hold up to 80 psi doesn’t mean you should run at that full time. He is right it will wear the tires faster. You can use the famous “chalk line rest” to determine the appropriate pressure for your load. I too have E rated tires on my truck and I run at 40 psi for optimum comfort/wear combination. I bumpy it’s up to 50 when hauling heavy loads.

wildtoad · 11-15-2022, 09:51 AM

I assume you are referring to the tire pressure on side of the tire which is the MINIMUM pressure required to support the MAXIMUM load the tires can support (Usually interesting but useless information). The weight of the trailer is not on the truck tires. The weight of the TT is insignificant except for tongue weight and/or the Gross Combined Weight Rating (GWCR). My advice is to take your truck and trailer to a weigh station and get them both weighed set to how you will be traveling. Full fuel, full water, food, people, toys, etc. Get weights for truck steer tires, rear tires, and trailer. Then use tire manufacturers chart to determine actual pressure needed to support the weights. I suspect the tire pressures will be closer to the 45 than the 80.

Add the weight of the truck to the weight of the trailer to determine if you have exceeded the GCWR.

glwinger · 11-15-2022, 10:16 AM

Quote:

Originally Posted by BayRunner

As the tech mentioned, just because the tire reads it can hold up to 80 psi doesn’t mean you should run at that full time. He is right it will wear the tires faster. You can use the famous “chalk line rest” to determine the appropriate pressure for your load. I too have E rated tires on my truck and I run at 40 psi for optimum comfort/wear combination. I bumpy it’s up to 50 when hauling heavy loads.

Another way to check the tread pattern is to wet the driveway in front of the tires and drive through the water to a dry spot.

You will see the contact patch of the tread.
I also have LRE tires on my 1/2 ton. run them at 45psi for daily driving and only increase them to 55-60 when hauling may trailer.

Crasher · 11-15-2022, 03:03 PM

Every now and then I hear of someone inflating to the sidewall pressure whether needed or not. You will get the best longevity, traction, and wear by weighing the truck inflating to the recommended psi in the load inflation chart.

Cumminsfan · 11-15-2022, 04:14 PM

When I added some E rated Michelin LT's to my F150 Discount Tire said 50 psi the max needed. I usually ran 45 psi. 80 psi is total overkill. Tires only need to be inflated to the load they're carrying.

Crasher · 11-15-2022, 05:29 PM

Follow up to post #6. To prove my point about the load inflation charts accuracy, several years ago, I did a trial on a 2002 Avalanche that weighed 6200#. The door said 33 or 35 psi for the tires. I knew that was for the maximum rated load. After weighing it and checking the load inflation table, I ran 28 psi unless I had a load which I weighed and set the pressures. I also rotated the tires every 10,000 miles. 4 1/2 years later with 83,000 miles on, I replaced them. There was still safe tread, but was going on a trip. The tread wear was uniform and even. The design engineers that write the load inflation tables know what they ae doing. I follow one on all of our vehicles.

Toby Dog · 11-16-2022, 04:14 AM

So there is 80 PSI in the tires. What about the wheel rating and the valve stems? Something for the OP to think about.
What you're pulling is not the question, it's what you are carrying.

jadatis · 11-16-2022, 05:54 AM

If you now give tire-specifications of TV, I will make a pressure/ axleload list for them.

Make it with my made spreadsheet, in wich an even safer formula used then the official ones, and give 90% of that loadcapacity calculated.
This gives highest pressure, with max reserve, but still acceptable comfort and gripp.
But if you want other reserves write it and I fill that in.

Then you " ONLY" have to determine the axleloads acurate, the most tricky part in it all.

I think your OEM tires where P-tires, and recomended pressure for those is mostly in the 35 psi range.
Then E-load ( AT 80 psi) needs about 10 psi more, so 45 psi could be spot on.

But I can be wrong, weighing and calculation makes it shure.

Need 3 things from tire.
1. Maximum load or loadindex
2, loadrange or better pressure behind AT, is your 80 psi
3. Speedcode, less important, all LT above Q speedrate are calculated in maxload for 160kmph/99mph.

Wrktfsh · 11-16-2022, 06:01 AM

Running 80 psi in 1/2 ton truck tires will loosen all your dental work

Ray,IN · 11-16-2022, 01:14 PM

I've never heard of or seen a 1500/½T pickup with OEM rims designed for 80PSI.

Psneeld · 11-16-2022, 02:30 PM

I checked some charts for my 245/70 R 19.5s load range G.

They recommended 80 psi (the lowest the chart went for that tire). The RV "door" sticker recommends 82. 80 psi was for axel weights way above my actual axel weights, between 1000-2000 pounds.

But based on axel/tire actual weights for a 18000 pound vehicle, my guess would be tire pressures say as low as 50 psi which seems low and maybe why the chart stops at 80, though probably way overinflated for the actual weight.

Any tire experts care to comment?

I feel that the 82 recommended is probably a good starting point...the tire sidewall max pressure is 110 psi.

Gary RVRoamer · 11-16-2022, 03:27 PM

Psneeld: Don't ever go below the minimum entry in the inflation table.

You apparently have tires and axles that are more than just adequate for your loads. That's a generally a good thing, though maybe a bit more costly at replacement time. In any case, if your scaled axle weights really are below that the inflation tables show for 82 psi, you can feel safe at 80 rather than 82. However, you probably won't notice a difference - 2 psi is not significant.