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Discussion Starter · #1 ·
For all of you folks that either ran new tires 305x70x17, 33x12.50x17, 315x70x17, 35x12.50x17's or something other, what are you running for air pressure and are you getting any TPMS errors? The stock Toyo's want to be in the 50 psi range I believe. The tires I'm looking at want to be in the 35-40 psi range. Will I be fighting the idiot light all the time?
Thanks
TodI
 

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Several people in this and other forums find 55 to be a pretty good setting for the front on the stock tires. There are a few, of course, that want a wallowing, ultrasoft ride like they're in boats. Tire pressure settings are based on tire loadings, by the manufacturers. Not sure why you'd want 40- psi. Softer ride means tires heat up faster, and damage themselves quickly at highway speeds. To move to a 40psi setting and be within good manufacturer guidelines, you'd have to on 40+ inch tires with 18+ inch widths, I'm guessing. And yes, you'll get TPMS errors until the computer dies or someone figures out how to override it.
 

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Discussion Starter · #3 ·
W
Several people in this and other forums find 55 to be a pretty good setting for the front on the stock tires. There are a few, of course, that want a wallowing, ultrasoft ride like they're in boats. Tire pressure settings are based on tire loadings, by the manufacturers. Not sure why you'd want 40- psi. Softer ride means tires heat up faster, and damage themselves quickly at highway speeds. To move to a 40psi setting and be within good manufacturer guidelines, you'd have to on 40+ inch tires with 18+ inch widths, I'm guessing. And yes, you'll get TPMS errors until the computer dies or someone figures out how to override it.

Well BFG recommends 35 to 45psi in their KO2 AT's on their 35's and max pressure of 65psi at max load.. Of all the off-road tires I've run, ground Hawgs, super swampers, Dick Cepek, duratracs, etc, I've never run them at 55psi, so I was curious as to what other people are running pressure wise in other tires besides the toyo AT's.
 

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Actually, BFG and pretty much every tire manufacturer recommends you follow the tire pressure recommendations of the vehicle manufacturer. They don't recommend anything else. All the experts say to keep your tires inflated to the vehicle maker's specifications, as directed on the sticker in your truck's tire information placard on your door jam. By experts, I'm referring to the tire making industry itself, the experts in the tires. Here are the official statements:

Tire Industry Association (TIA) - The Tire Industry Association (TIA) is an international non-profit association representing all segments of the tire industry, including those that manufacture, repair, recycle, sell, service or use new or retreaded tires, and also those suppliers or individuals who furnish equipment, material or services to the industry. TIA is the leading authority in the tire industry for advocacy and training. TIA has over 7,000 members from all 50 states and around the globe.

Rubber Manufacturers' Association (RMA) [you can get their brochure on tire safety for free, but you have to go through their shopping cart system] - The Rubber Manufacturers Association (RMA), originally named the Rubber Club of America, was established in 1915 to serve rubber products manufacturers. Since its inception, RMA has evolved and now solely represents tire manufacturers that produce tires in the U.S.

National Highway Traffic Safety Administration (NHTSA) - the government body making national recommendations

In addition, every tire manufacturer I checked with - Toyo, BFG, Goodyear, Firestone, Michelin, etc. They all say the same thing. Michelin even goes so far as to state: Compare the measured psi to the psi found on the sticker inside the driver’s door of your vehicle or in owner’s manual. DO NOT compare to the psi on your tire’s sidewall.

When you oversize tires, you can get similar information from the load tables offered by the tire maker. For example, Nitto's load tables are readily found here.
 

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Gotta agree with @johnj here
 

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I think it's worth discussing the load tables a little. The tire manufacturers generally defer to the vehicle manufacturers because of the vehicle weight. They provide the same load ratings to the truck maker, and the truck maker reviews the GVWR and establishes an inflation level.

The normal method for using them is to divide the GVWR by 4 to get individual tire load on its axle. Rebel GVWR is 6800 lbs. That includes payload and passengers. That's 3400 per axle, 1700 per tire. Then expected conditions are calculated. For example, the Rebel's rated for offroading. There's a good chance it's going to be supported on 3 of the 4 tires on occasion, and sometimes maybe only 2. So they add in a load factor for that - a safety margin, essentially.

You can work backwards to figure out what Ram's load calculation is for the Rebel. Looking at Toyo's tire inflation tables for the A/T, I found:
Text Font Number Rectangle

LT285/70/17 inflated to 55 psi has a load limit of 2900 lbs.

Using the Nitto tire load chart, using the 17" rims, I could put a variety of Nitto tires on the same rims. Each has its own pressure rating based on that load limit of 2900 lbs. All of these are 285/70/17s unless otherwise noted.

EXD Grappler AWT: 80 psi
Trail Grappler MT: 80 psi
Mud Grappler: 65 psi (these are 12" wide vs 11")
 

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I'm running my Bfgoodrich 315/70's at the stock pressure just so I don't have any tpms messages. It rides the same as stock
 

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Discussion Starter · #8 ·
I've never run them at 55psi, so I was curious as to what other people are running pressure
Gotta agree with @johnj here
wise in other tires besides the toyo AT's.[/QUOTE]

So what do you run a load range D at 3000lbs that is asking for a max pressure of 50psi? I'm not towing 10K pounds. I just didn't want a load range E tire and have to deal with a stiff sidewall. My new tires want 35 to 40psi with max of 50 and not the 55psi that the TPMS is looking for.
Dealer isn't willing to change setting, but I hear other dealers in other states (Other then Michigan) are willing to adjust the TPMS settings
Todd
 

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I run 55psi in the front and 50 in the rear and no issues with the tpms coming on.
 

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If your tire max PSI is 50, I would run them at 45. I wouldn't recommend running a tire at its max. One of the things I'm looking for in a new tire is that it has a max PSI of 65 that way I can use the truck manufacture PSI rating.
 

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A 10 ply tire max psi is 65psi. The toyo tires on the rebel from the factory are 10ply.
 

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It's super easy to find load and pressure charts for most tires on the manufacturer sites. If you have a tire you prefer it takes only a minute to get the right pressure for the truck.
 

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I am not at home and near my comp so not searching data very well. I found a list of BFGoodrich&tireModel Goodrich Ko2 tire sizes on tirerack.com. According to their spec list in the middle of this page the max air pressure for 35x12.5r17 is 65psi and max load is 3100+ lbs.

The only 35s they list with a max pressure of 35psi are r15s.

BFGoodrich All-Terrain T/A KO2

BF Goodrich doesn't have a tire load pressure chart handy on its site, probably buried in dealership data which I am not having any luck finding. The only guidelines I can find - in many places on their site - is to follow the recommendation of the vehicle manufacturer.
 

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Discussion Starter · #15 ·
I think it's worth discussing the load tables a little. The tire manufacturers generally defer to the vehicle manufacturers because of the vehicle weight. They provide the same load ratings to the truck maker, and the truck maker reviews the GVWR and establishes an inflation level.

The normal method for using them is to divide the GVWR by 4 to get individual tire load on its axle. Rebel GVWR is 6800 lbs. That includes payload and passengers. That's 3400 per axle, 1700 per tire. Then expected conditions are calculated. For example, the Rebel's rated for offroading. There's a good chance it's going to be supported on 3 of the 4 tires on occasion, and sometimes maybe only 2. So they add in a load factor for that - a safety margin, essentially.

You can work backwards to figure out what Ram's load calculation is for the Rebel. Looking at Toyo's tire inflation tables for the A/T, I found: View attachment 792
LT285/70/17 inflated to 55 psi has a load limit of 2900 lbs.

Using the Nitto tire load chart, using the 17" rims, I could put a variety of Nitto tires on the same rims. Each has its own pressure rating based on that load limit of 2900 lbs. All of these are 285/70/17s unless otherwise noted.

EXD Grappler AWT: 80 psi
Trail Grappler MT: 80 psi
Mud Grappler: 65 psi (these are 12" wide vs 11")
So JohnJ, you're telling me I should run my cooper MTP's higher then what the sidewall says for max inflation?
Here are the specs and the sidewall says max inflation 50psi

Size Diameter Width Tread Depth Tread Width Rim Range Load Range Max Load Max psi Weight Revs/Mile
LT315/70R17

34.5" 12.8" 19.5/32" NA NA D 3195 lbs NA 62 lbs 602

D range with a load max of 3195lbs, weight of 62lbs and revs of 602?

RIght from Cooper websiste
Do not exceed the maximum inflation pressure shown on the tire sidewall. Over inflated tires (over the maximum molded on the tire sidewall) are more likely to be cut, punctured or damaged by sudden impact from hitting an
 

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Discussion Starter · #16 ·
I run 55psi in the front and 50 in the rear and no issues with the tpms coming on.

And are you running a tire that has a max on the sidewall of 50? I get it that load range E tires like higher PSI, the original question is what is anybody doing who is running a tire that has a max psi of 50 on their rebels... Did they get the TPMS re-progammed from the dealer or are they dealing with the low tire light on?
 

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So JohnJ, you're telling me I should run my cooper MTP's higher then what the sidewall says for max inflation?
Here are the specs and the sidewall says max inflation 50psi

Size Diameter Width Tread Depth Tread Width Rim Range Load Range Max Load Max psi Weight Revs/Mile
LT315/70R17

34.5" 12.8" 19.5/32" NA NA D 3195 lbs NA 62 lbs 602

D range with a load max of 3195lbs, weight of 62lbs and revs of 602?

RIght from Cooper websiste
Do not exceed the maximum inflation pressure shown on the tire sidewall. Over inflated tires (over the maximum molded on the tire sidewall) are more likely to be cut, punctured or damaged by sudden impact from hitting an
Nope, not at all, @Mtudb24. I have only stated so far that tire manufacturers say to follow the guidelines of the vehicle makers (and I copied in direct quotes from tire companies, then pointed out that tire changes can be addressed with load tables, with which you disagreed.)

Anyone that thinks that through would realize it applies to the tires the maker stuck on the vehicle, and that things change when you change the tires. So I also added a post about load tables for when you swap out the stock tires with something else. That should help most people determine what tire pressure they need to be running. I used Nitto's load chart for some of their tires as an example.

It's clear that Ram thinks a 2900 lb load rating is about right for off-roading in the Rebel.

Cooper is like BF Goodrich in that they don't provide a load table for recommended tire pressures at load on the web. A good load table will list different loads for the tire, with different air pressures to support those loads properly, according to the tire maker. They may make those load tables available to their dealers. It would be good business sense. Some treat them as a trade secret, which means I won't buy their tires.

As it is, Cooper's recommendations to you are conflicting. This is what they say in plain, clear English, right from Cooper's web site regarding proper tire inflation. Read it.
The recommended inflation pressures for tires are specified in pounds per square inch (psi) or kilopascals (kPa) as indicated on the vehicle tire placard, certification label or in the owner's manual. Never set tire inflation pressures below the recommended inflation pressure found on the vehicle tire placard, certification label or owner's manual. Under inflation causes excessive heat build-up and internal structural damage that may lead to a tire failure, including tread/belt separation, even at a later date. Do not exceed the maximum inflation pressure shown on the tire sidewall. Over inflated tires (over the maximum molded on the tire sidewall) are more likely to be cut, punctured or damaged by sudden impact from hitting an obstacle, such as a pothole.​

Clearly they don't want you to set the pressure above 50psi, or below 55psi. :) Of course, Ram is basing their numbers on E-rated tires. Hence the load table really is needed.

When you don't have a load table, you can also use simple calculations, if they exist.

You can keep disagreeing with me all you want. I'm just trying to help you find what you want. I've pointed out how to use the load tables to your advantage. In the case of Cooper tires, which you hadn't mentioned previously, you're probably going to have to contact them directly, or your local dealer, to get an accurate load (inflation) table.

Otherwise, it's a swag. If it were me, I'd be running those at 45+psi minimum, because their max load is close to Ram's load calculation already. Plus that might keep the TPMS from bitchin'.

Or you can now buy the $600 Trinity tuner which DiabloSport claims can adjust the TPMS threshold. But since you have a 2015/16 Ram, you also have to buy their PCM as well, for another $600 (or $1000 total if you buy both at once).

No matter what you do, you've disagreed with tire maker guidelines, including Cooper's, and with my suggestions and examples on using load tables to reverse-engineer the pressure you want. And each time you mention tires you switched tire brands and models. I give up trying to keep up. You're on your own.
 

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Hi,
I want to buy new tires, don't get me wrong the tires that come with the rebel are good but I wanted something better. Without changing the rims can I go up a size or two without having to lift anything, What sizes would be recommended also?
 

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Discussion Starter · #20 ·
Nope, not at all, @Mtudb24. I have only stated so far that tire manufacturers say to follow the guidelines of the vehicle makers (and I copied in direct quotes from tire companies, then pointed out that tire changes can be addressed with load tables, with which you disagreed.)

Anyone that thinks that through would realize it applies to the tires the maker stuck on the vehicle, and that things change when you change the tires. So I also added a post about load tables for when you swap out the stock tires with something else. That should help most people determine what tire pressure they need to be running. I used Nitto's load chart for some of their tires as an example.

It's clear that Ram thinks a 2900 lb load rating is about right for off-roading in the Rebel.

Cooper is like BF Goodrich in that they don't provide a load table for recommended tire pressures at load on the web. A good load table will list different loads for the tire, with different air pressures to support those loads properly, according to the tire maker. They may make those load tables available to their dealers. It would be good business sense. Some treat them as a trade secret, which means I won't buy their tires.

As it is, Cooper's recommendations to you are conflicting. This is what they say in plain, clear English, right from Cooper's web site regarding proper tire inflation. Read it.
The recommended inflation pressures for tires are specified in pounds per square inch (psi) or kilopascals (kPa) as indicated on the vehicle tire placard, certification label or in the owner's manual. Never set tire inflation pressures below the recommended inflation pressure found on the vehicle tire placard, certification label or owner's manual. Under inflation causes excessive heat build-up and internal structural damage that may lead to a tire failure, including tread/belt separation, even at a later date. Do not exceed the maximum inflation pressure shown on the tire sidewall. Over inflated tires (over the maximum molded on the tire sidewall) are more likely to be cut, punctured or damaged by sudden impact from hitting an obstacle, such as a pothole.

Clearly they don't want you to set the pressure above 50psi, or below 55psi. :) Of course, Ram is basing their numbers on E-rated tires. Hence the load table really is needed.

When you don't have a load table, you can also use simple calculations, if they exist.

You can keep disagreeing with me all you want. I'm just trying to help you find what you want. I've pointed out how to use the load tables to your advantage. In the case of Cooper tires, which you hadn't mentioned previously, you're probably going to have to contact them directly, or your local dealer, to get an accurate load (inflation) table.

Otherwise, it's a swag. If it were me, I'd be running those at 45+psi minimum, because their max load is close to Ram's load calculation already. Plus that might keep the TPMS from bitchin'.

Or you can now buy the $600 Trinity tuner which DiabloSport claims can adjust the TPMS threshold. But since you have a 2015/16 Ram, you also have to buy their PCM as well, for another $600 (or $1000 total if you buy both at once).

No matter what you do, you've disagreed with tire maker guidelines, including Cooper's, and with my suggestions and examples on using load tables to reverse-engineer the pressure you want. And each time you mention tires you switched tire brands and models. I give up trying to keep up. You're on your own.

#17 johnj, Sunday at 11:44 AM

JohnJ
I'm not going to argue with you. It's a waste of time. If you go back in the threads, it was a simple question.. Does anybody who runs something in a size of other then stock size that isn't a load range E and have a max pressure on the sidewall of 50psi what did you do to fool the TPMS? And if you like to go back and re-read my post, I never said I was running anything on my Rebel then Cooper MTP's. I said I have run other tires from Super Swamper, Ground Hawgs, and other brands on my other trucks that never asked for 55psi. Its because all my other trucks were never load range E and asking tor that high of a pressure. My k5 blazer had Super Swampers and Ground Hawgs (no TPMS). My 2003 Tahoe had Super Swampers. My 1996 Chevy ZR2 had Swamper Thornbirds . My 2007 Chevy Silverado had Buckshot Mudders. All those tires asked for 35 or so PSI.
Be done with trying to help me. I don't really care as your tire pressure calculations aren't helping me. Even at 50PSI in the Cooper MTP's, the light is still on asking me to inflate my front tires to 55PSI. I will not inflate those tires past the max tire inflation noted on the sidewall.

I fall back to my original question to the forum. Those that are running a aftermarket tire that are not load range E and don't have a 55PSI tire rating, what are people doing to fool the TPMS. You don't have any real world experience on your Rebel of this condition and anything you have told me is not turning my light off. I will deal with the light or will get a programmer to fix the situation.
Thanks for your time.
 
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