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Old 08-09-2021, 06:36 PM   #1
Campitupcouger
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GoodYear TrailRunner AT 275 / 60R20 Towing Tire Pressure

I just bought a new 2021 GMC Sierra 6.2 L X31 Off Road with GoodYear TrailRunner AT 275 / 60R20 for tires. The Max Cold PSI for these tires is 51 PSI. When towing my Keystone Cougar TT fully loaded, should I air up to the Max PSI Cold? In general, I have seen many opinions mostly land on setting them to the Max PSI. The Trailer Tires are always at the Max PSI.
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Old 08-09-2021, 09:41 PM   #2
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These tires donít appear to be LT truck tires, so might be P metric tires and with the load of the trailer, you might be over extended with these tires. Hopefully the tire gurus will have a better answer.
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Old 08-10-2021, 03:14 AM   #3
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With that truck you will need every PSI available. Keep them at the max cold 51 PSI. Your tires are not LT, but are 10 ply rating. Make sure you have the best WDH you can afford with the best sway control. You will need it.
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Old 08-10-2021, 04:05 AM   #4
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Saw this note on itstillruns.com:
Significance

SL-rated tires are the lowest load capacity tires that are used on trucks and SUVs. If your truck has load range SL tires, consider upgrading the tire load capacity, or be careful how much cargo you haul in your truck.
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Old 08-10-2021, 05:38 AM   #5
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I bet your truck looks like a beast and is a real testosterone booster. Sounds like a great off road truck. Problem is, off road trucks make lousy trailer haulers. Not to rain are your parade but you need to be aware of the difference in a tow vehichle and an off road vehichle. The things that make it good for off roading like large pliable tires for traction, extra suspension travel for articulation, and a high center of gravity for clearing obstacles are countrr ptoductive for towing.

To answer your question yes you will need full inflation available for the reasons listed above. With the trailer listed inbyour bio you're likely close to a 1/2 ton truck capacity so make sure you have a quality weight distributing hitch with BUILT IN SWAY 4 POINT SWAY CONTROL. The hitch is not he item to be thrifty on as it's the only thing between you and the thousands of pounds behind you. Good luck and travel safe.
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Old 08-10-2021, 07:41 AM   #6
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The tires are not LT tires, and are intended to give a nice ride while still allowing a degree of medium duty service. When I had similar rated tires (previous owner had them installed), I would keep them at 51 psi all through towing season and then air them down to 34 psi for the winter (based on the door jamb sticker). I have since installed LT tires with an 80 psi rating like what came on my truck new.
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Old 08-10-2021, 07:49 AM   #7
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Just to reiterate what has been said, air up to max psi. A 1/2 ton needs every bit of control it can get pulling an RV. Your profile shows an Equalizer hitch so you have a good hitch - just set it up right.

It appears your tires are "SL", or standard load, tires. Here is a description of what that means;

"A classification of SL means it's a standard load tire. Most passenger tires are standard load, but standard load tires can also be used on some lighter trucks and SUVs. If your vehicle came with SL tires as it's original equipment, then SL tires are a suitable replacement."

Note that it says "most passenger tires are SL" and SOME "lighter trucks". Reading between the lines it basically says to me that you have passenger car tires on there with an AT tread. If it were me I would run at max PSI when towing until I put a new set of heavier tires on the truck.....by the end of the week.
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Old 08-10-2021, 07:52 AM   #8
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Really the question should be are the tires up to the task or able to carry that load. Read the tires max. wt. rating and weigh your combo to get the real load on the rear axle. If it's overloading the tires, get better tires. If it's not of course air them up to max.
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Old 08-10-2021, 01:28 PM   #9
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I made necessary correction. It seems that 10 ply rating load range E generally would denote LT. Discount tire thought so, and I took the word of that particular site. Shame on me, I'll look further next time.
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Old 08-10-2021, 03:22 PM   #10
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I can honestly say I have never bought a vehicle that had good tires from the dealership. I will for sure be looking for top of the line in the next go round. Thanks so much for all of the great feedback and thought! Always good to get different perspectives.
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Old 08-11-2021, 03:19 PM   #11
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Quote:
Originally Posted by Campitupcouger View Post
I just bought a new 2021 GMC Sierra 6.2 L X31 Off Road with GoodYear TrailRunner AT 275 / 60R20 for tires. The Max Cold PSI for these tires is 51 PSI. When towing my Keystone Cougar TT fully loaded, should I air up to the Max PSI Cold? In general, I have seen many opinions mostly land on setting them to the Max PSI. The Trailer Tires are always at the Max PSI.
Without a full description this is how I see it:

Your tires are ISO Euro Metric. They are (SL) and have their own load inflation chart. Do not use Euro XL or USA P inflation charts. Look at the service description on the tire sidewall. The P tires will have the lowest Service Description, maybe 114 the SL ties are always a little higher starting at 115. The XL tires may be 116.

Depending on the tire manufacturer and the purpose of the tire the load inflation charts may differ with maximum load capacity topping out at somewhere near 36 - 42 PSI. The maximum sidewall pressure may be 50/51 PSI. From the 36/42 PSI to the 51 PSI there is no increase in load capacity, just tire stiffness.

Here is an inflation chart for you to ponder.

https://tirepressure.com/metric-tire...nflation-table

Here are what I suspect are the specs for your tires.

https://www.tirerack.com/tires/Spec....TrailRunner+AT
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Old 08-11-2021, 05:33 PM   #12
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I would actually look at your truck door and see what your axle rating is and the recommended pressure. Since those were oem on your truck they will exceed the able rating at the recommended pressure. As long as you aren't exceeding that I would run then at or slightly above recommended pressure. If you set them to max you will likely have heavy wear on the center of the rear tires. The manufacturer set the specs to a safe psi for the axle rating. By the way I recently bought this same tires for my ram and they are absolutely better than the wrangler sra they replaced.
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Old 08-19-2021, 09:07 AM   #13
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20" tires for the greatest part are "looks" tires not working tires. Probably also caused the payload capacity to be derated also.
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Old 08-19-2021, 06:45 PM   #14
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115S Rated

Be careful out there!
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Old 08-20-2021, 06:43 AM   #15
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Let's see: P metric tires with flexible sidewalls... Great for rock climbing, hitting potholes and "airing down for sand"... Not so great for stability when towing. So....

The come in Standard load, Extra Load and can be "aired up to 51PSI". That makes the "flexible sidewalls a bit less flexible" but won't stop the sidewalls from "rolling with trailer sway"... So.....

When compared to a LT tire, they're going to be "more squishy" and the trailer lateral movement is going to be "felt more in the seat of your pants"... So....

As with most "anything in these times of highly specialized products" tires are "also selective for the specific task"... With P metric tires, towing isn't high on the list of plusses....So....
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Old 08-20-2021, 03:26 PM   #16
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According to Tire rack, they are LT tires

https://www.tirerack.com/tires/tires..._Tire&code=yes
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Old 08-20-2021, 04:01 PM   #17
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Quote:
Originally Posted by Mr Mojo View Post
According to Tire rack, they are LT tires

https://www.tirerack.com/tires/tires..._Tire&code=yes

Those are big tires on that truck and only have a rating of 51 psi. In my experience that isn't in the realm of an LT tire that size. I'm thinking you read that paragraph that referenced "LT tires" but wasn't specifically speaking to this tire. Here's a link to the same tire that has a better descriptor:

https://www.discounttire.com/buy-tir...ner-at/p/87727

Notice right under the name of the tire it gives a better description and it that line it specifies "SL" for standard load. Then here's this - read the first paragraph:

Passenger Tires
Since most P-metric passenger tires are manufactured in the standard load range, they will have nothing branded on their sidewalls or may be branded standard load and identified by an SL in their descriptions, as in P235/75R-15 SL.

Extra load P-metric tires will be branded extra load, and identified by an XL in their descriptions, as in P235/75R-15 XL.

Light load P-metric tires will be branded light load, and identified by an LL in their descriptions, as in P285/35R-19 LL.


And here's the rest. Note that LT tires do not use SL/XL etc., they use letters - mine are E;

https://www.tirerack.com/tires/tiret...&affiliate=HM5
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Old 08-20-2021, 06:17 PM   #18
Mr Mojo
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Quote:
Originally Posted by sourdough View Post
Those are big tires on that truck and only have a rating of 51 psi. In my experience that isn't in the realm of an LT tire that size. I'm thinking you read that paragraph that referenced "LT tires" but wasn't specifically speaking to this tire. Here's a link to the same tire that has a better descriptor:

https://www.discounttire.com/buy-tir...ner-at/p/87727

Notice right under the name of the tire it gives a better description and it that line it specifies "SL" for standard load. Then here's this - read the first paragraph:

Passenger Tires
Since most P-metric passenger tires are manufactured in the standard load range, they will have nothing branded on their sidewalls or may be branded standard load and identified by an SL in their descriptions, as in P235/75R-15 SL.

Extra load P-metric tires will be branded extra load, and identified by an XL in their descriptions, as in P235/75R-15 XL.

Light load P-metric tires will be branded light load, and identified by an LL in their descriptions, as in P285/35R-19 LL.


And here's the rest. Note that LT tires do not use SL/XL etc., they use letters - mine are E;

https://www.tirerack.com/tires/tiret...&affiliate=HM5
to be honest I stopped reading after I saw "LT", but I agree that those tires are too "big" and with a low profile, must give a pretty harsh ride.
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Old 08-21-2021, 01:02 PM   #19
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Quote:
Originally Posted by Mr Mojo View Post
to be honest I stopped reading after I saw "LT", but I agree that those tires are too "big" and with a low profile, must give a pretty harsh ride.
These tires give a good ride at least in my 1500. They actually exceeded the weight rating on oem tires and are fine for any trailer I ought to tow with a 1500. GAWR on mine is 3900lbs and the tires support around 5350. Op's axle may support more but can't be all that much as it's still a 1500. This tires will do the job if you keep within vehicle specs for payload.
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Old 08-21-2021, 01:15 PM   #20
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Quote:
Originally Posted by sourdough View Post
Those are big tires on that truck and only have a rating of 51 psi. In my experience that isn't in the realm of an LT tire that size. I'm thinking you read that paragraph that referenced "LT tires" but wasn't specifically speaking to this tire. Here's a link to the same tire that has a better descriptor:

https://www.discounttire.com/buy-tir...ner-at/p/87727

Notice right under the name of the tire it gives a better description and it that line it specifies "SL" for standard load. Then here's this - read the first paragraph:

Passenger Tires
Since most P-metric passenger tires are manufactured in the standard load range, they will have nothing branded on their sidewalls or may be branded standard load and identified by an SL in their descriptions, as in P235/75R-15 SL.

Extra load P-metric tires will be branded extra load, and identified by an XL in their descriptions, as in P235/75R-15 XL.

Light load P-metric tires will be branded light load, and identified by an LL in their descriptions, as in P285/35R-19 LL.


And here's the rest. Note that LT tires do not use SL/XL etc., they use letters - mine are E;

https://www.tirerack.com/tires/tiret...&affiliate=HM5
You have referenced the correct designated size. However, it's a ISO Euro-Metric and those sizes have their own load inflation charts.

ISO Metric (Metric or Hard metric) vs. P-metric: It is important to know which standard is applicable for any given tire size designation as the load capacity may differ at any inflation pressure value. The TRA developed the P-metric standard and the ETRTO developed the ISO Metric/Hard Metric standard. For example, TRA P225/55R17 95T has a maximum load capacity of 1521 lbs. @ 35 psi (see Table 1) while 225/55R17 95T has a maximum load capacity of 1609 lbs. @ 36 psi.
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