The Definitive Word on Tire Pressures

[Trawlerphil]

I was exhausted reading opinions on tire pressures from the RV sites so I decided to ask the manufactures for the truth. I sent the following to them: I have a 2012 Tundra 4X4 with the towing package and the 5.7 V8 engine. We tow a 9,000 lb. 5th wheel and the Tundra is my daily driver when not towing. I currently have load range C on the front, but I put load range E on the rear. My original logic was the V8 was the same weight towing or not so I didn't think the load range C would be an issue. I was wrong. There is a 1 1/4" size difference in circumference between the front and rear which drives the "nannies" crazy so I'm considering putting the same size load range E tires on both front and rear.

My question is what should the tire pressures be front and rear if I use load range E all around when towing a 9,000 lb. 5er? Also, what should the tire pressures be front and rear when I'm using the truck as a daily driver?

Now, you'd think this is a simple pair of relevant questions founded on a fully loaded truck vs an empty truck, and load range E vs load range C, but Michelin's response was essentially "read the sidewall of the tire", Firestone's response was "The tire pressure is based on your vehicle, not the tires." She directed me to a site where the standard front and rear pressures for a Tundra with standard tire on it. Goodyear got the Darwin Award for recommending load range E tires should be going with the door placard regardless of load range and for towing the 5 wheeler he said, "I would recommend going with a pressure around 5-10 higher than is what on the door placard to start, then slowly adding more if you feel the ride to be unstable". I'll bet their legal department would love that explanation!

Now, I'm no engineer, but I do know under-inflation generates heat which contributes to tire failure. I know the 80 PSI max for load range E tires will handle the maximum load rating, but what should the inflation be with no load other than the truck itself? I also know that if all of the tires with no load are set to 80PSI, my bladder feels their pain so I don't think my questions are absurd and should require an answer from the manufacturers. Why I can't get one is beyond me.

Are all of these manufacturers incompetent or do they just hire chat room technicians who can only distribute standard specifications and don't know squat about tires? Inquiring minds want to know!

Michelin sent me a survey on my interaction with their CSR. I copied all of the above into my response and they got back to me with a real answer!

Phil, we totally understand how you feel. Calculating the correct inflation pressure is not easy.
For daily driving with tire size LT275/65R20 tires on your Tundra, we recommend 40 psi front and 45 psi rear. Pressures should be checked when the tires are cold.

Additional psi would be calculated depending on the amount of tongue weight added to the vehicle when towing the trailer. The rear axle would need to be weighed without the trailer attached and with the trailer attached then adjust the psi accordingly. Following is the load/psi chart for tire size LT275/65R20 LRE:

2080 lbs @ 35 psi
2280 lbs @ 40 psi
2475 lbs @ 45 psi
2680 lbs @ 50 psi
2850 lbs @ 55 psi
3030 lbs @ 60 psi
3195 lbs @ 65 psi
3375 lbs @ 70 psi
3540 lbs @ 75 psi
3750 lbs @ 80 psi
We hope that your issue has been resolved or addressed to your satisfaction. If we can assist you further, please respond to this email or call us at 866-866-6605 (toll-free) between 8:00 a.m. and 8:00 p.m. EST Monday through Saturday.
We appreciate your business and thank you for choosing Michelin.
Sincerely,
Suzanne
Consumer Care Department
Certified Michelin Product Expert

Finally, a real answer!

[Airdale]

Originally Posted by Trawlerphil

Finally, a real answer!

But, it’s inaccurate. It does not follow established tire industry standards and the person providing you that information should have known that.

Here is another Michelin quote from their industry standards document: “The vehicle manufacturer selects the size and type of tires for their vehicles. They perform the necessary testing to establish the vehicles’ optimized operating tire inflation pressures which can be found on the vehicle placard (located on the inside of the driver's door) and in the vehicle owners’ manual.”

“If the tires on your vehicle are the same size as the original equipment tire, inflate them to the pressures indicated on the placard.”

When the vehicle manufacturer determines there is a need for different inflation pressures for towing heavy loads they will present them in the vehicle owner’s manual.

Owner’s, such as yourself always have the option to use inflation pressures anywhere in between what has been recommended and what is listed on the tire sidewall for the tire’s maximum load capacity. Do not exceed the wheel’s PSI limit.

For more detailed information you can browse the reference below. It’s an approved tire industry document.

https://www.ustires.org/sites/defaul...TruckTires.pdf

[lbrjet]

I don't see anything Michelin said that is inaccurate.

[Trawlerphil]

You stated "If the tires on your vehicle are the same size as the original equipment tire, inflate them to the pressures indicated on the placard". Clearly mine are neither the same size nor the same load-range so the strategy of getting a definitive answer from the manufacturer of the tires seems reasonable. I embarrassed them for providing a boiler-plate answer so they took the time to provide a real answer based on my real tires and load. For that, I am grateful.

[Macrosill]

Unless I missed something, Michelin's definitive answer was to inflate the tire to the proper pressure based on the load.
That info is found in a tires load inflation chart.

[Mad Cow]

One part of Michelin's recommendation is questionable. 40 psi front and 45 psi rear. A pickup is heavier in the front when empty than it is in the back, in normal daily driving, unless one is carrying around several hundred pounds of stuff in the back as part of their "normal" daily driving.

Michelin and BFG (also Michelin) are pretty good about providing load pressure charts for their tires. I follow those charts a lot.

The canned industry response that the vehicle OEM test tires and pressures to determine best pressure to run is a pile of something I stepped into today out on my property. The tire maker does all the R&D and provides the same load pressure recommendation you get on their charts to the OEM and that is what they go with. But, the OEM goes with the pressure for the max gross of the vehicle, not daily use. For the max gross of the pickup, the OEM is generally right on the recommended pressures. But that recommendation is usually much more than if the pickup is driven around daily empty.

This is especially of true of higher rated tires than passenger type.

I go with the tire maker recommendation when empty, and inflate accordingly if I am going to put weight on the pickup.

[lacamastraveler]

I chuckled when I saw the header, "The Definitive Word on Tire Pressures." Only if. There are lawyer answers, tire manufacture answers and dealer answers. If you put ten RVers in a room and ask the question you'll get eleven different answers.

I've Rv'd in everything from pickup camper to 16-ton diesel pusher.

My method is to weigh my RV front and back; 4 point if possible.

Obtain the pressure chart for my tires, adjust to the weight load and 5% for insurance.

I check my tires before every trip and use an after-market TPS on all tires to monitor pressure and temperature, including the toad.

In well over 150,000 miles of RVing I've never had a blowout, flat or uneven tire wear.

Of course, likely someone will respond that my way of doing it is not the definitive word on tire pressures and I will chuckle and agree!

[juice5]

Lacamas.....you have it right....on the button...utilizing knowns against variables...with your axioms...juice

[Cypressloser]

Originally Posted by Trawlerphil

I was exhausted reading opinions on tire pressures from the RV sites so I decided to ask the manufactures for the truth. I sent the following to them: I have a 2012 Tundra 4X4 with the towing package and the 5.7 V8 engine. We tow a 9,000 lb. 5th wheel and the Tundra is my daily driver when not towing. I currently have load range C on the front, but I put load range E on the rear. My original logic was the V8 was the same weight towing or not so I didn't think the load range C would be an issue. I was wrong. There is a 1 1/4" size difference in circumference between the front and rear which drives the "nannies" crazy so I'm considering putting the same size load range E tires on both front and rear.

My question is what should the tire pressures be front and rear if I use load range E all around when towing a 9,000 lb. 5er? Also, what should the tire pressures be front and rear when I'm using the truck as a daily driver?

Now, you'd think this is a simple pair of relevant questions founded on a fully loaded truck vs an empty truck, and load range E vs load range C, but Michelin's response was essentially "read the sidewall of the tire", Firestone's response was "The tire pressure is based on your vehicle, not the tires." She directed me to a site where the standard front and rear pressures for a Tundra with standard tire on it. Goodyear got the Darwin Award for recommending load range E tires should be going with the door placard regardless of load range and for towing the 5 wheeler he said, "I would recommend going with a pressure around 5-10 higher than is what on the door placard to start, then slowly adding more if you feel the ride to be unstable". I'll bet their legal department would love that explanation!

Now, I'm no engineer, but I do know under-inflation generates heat which contributes to tire failure. I know the 80 PSI max for load range E tires will handle the maximum load rating, but what should the inflation be with no load other than the truck itself? I also know that if all of the tires with no load are set to 80PSI, my bladder feels their pain so I don't think my questions are absurd and should require an answer from the manufacturers. Why I can't get one is beyond me.

Are all of these manufacturers incompetent or do they just hire chat room technicians who can only distribute standard specifications and don't know squat about tires? Inquiring minds want to know!

Michelin sent me a survey on my interaction with their CSR. I copied all of the above into my response and they got back to me with a real answer!

Phil, we totally understand how you feel. Calculating the correct inflation pressure is not easy.
For daily driving with tire size LT275/65R20 tires on your Tundra, we recommend 40 psi front and 45 psi rear. Pressures should be checked when the tires are cold.

Additional psi would be calculated depending on the amount of tongue weight added to the vehicle when towing the trailer. The rear axle would need to be weighed without the trailer attached and with the trailer attached then adjust the psi accordingly. Following is the load/psi chart for tire size LT275/65R20 LRE:

2080 lbs @ 35 psi
2280 lbs @ 40 psi
2475 lbs @ 45 psi
2680 lbs @ 50 psi
2850 lbs @ 55 psi
3030 lbs @ 60 psi
3195 lbs @ 65 psi
3375 lbs @ 70 psi
3540 lbs @ 75 psi
3750 lbs @ 80 psi
We hope that your issue has been resolved or addressed to your satisfaction. If we can assist you further, please respond to this email or call us at 866-866-6605 (toll-free) between 8:00 a.m. and 8:00 p.m. EST Monday through Saturday.
We appreciate your business and thank you for choosing Michelin.
Sincerely,
Suzanne
Consumer Care Department
Certified Michelin Product Expert

Finally, a real answer!

Fact is, the tire inflation numbers on the door pillar become obsolete the moment you replace the OEM tires, Period.
Some of the kids working at the tire shops don't even realize this and try to argue.

You did the right thing contacting Michelin and asking for a tire pressure chart, follow it as good as you can. If in doubt inflate the tires up to 5 psi higher, never lower.

The recommendation for 40 psi Front and 45 psi Rear seems odd, but maybe Michelin assumes a certain payload and wants you to add an extra 5 psi in the rear that works for these specific tires, IDK.
How this agrees with the 4x4 engaged, IDK. It may translate into excessive tire wear, wear in the transfer case and higher fuel consumption if you would leave it engaged on dry pavement but don't be afraid your truck will suddenly blow up and spontaneously combust.

[CaptnJohn]

On LR E, LR F, and LR g tires I run max sidewall pressure on the rear and a little less on the front, empty or towing. Current LR g are at 110 rear and 100 front. Rotated every 7500 miles and pressure adjusted. Have not had a lower rated tire in 30 years so cannot remember.

[moondog2000]

On my truck I have E rated tires and I always run them at 80 psi when i tow my trailer. This last January I was coming back from Quartzsite and I had a bounce in my right rear tire. I thought I had lost a wheel weight. When I took it in to Cosco they said I had a bubble in between the plys. I did take a lot of firewood down and no telling how much pressure was in the rear tires. I learned a big lesson on watching tire pressure. At 75 mph the bounce would sorta smooth out so I traveled at that speed through Arizona. Some one was watching over me.

[Cujo7240]

My 2017 F350 Superduty came with load range E tires and Ford recommends 80psi in the rear tires and 60psi in the front. I always felt that having 80psi in the rear when driving around empty just makes for a rough ride and reduced rear wheel traction, especially in the winter.
I asked Ford about this and their answer was to follow the Ford recommended values of course. I also figured if I lowered the rear tires to 65psi, the check tire pressure light woyld come on, which would annoy me.

[spock123]

My Silverado 3500 says 80 on the rear and 60 on the front but I get a better ride empty if I lower the rear to 60. A Silverado 3500 doesn’t have a onboard TPMS and my TST 507 is set a little lower than 60lbs for the rear tires

[5picker]

Originally Posted by Cujo7240

My 2017 F350 Superduty came with load range E tires and Ford recommends 80psi in the rear tires and 60psi in the front. I always felt that having 80psi in the rear when driving around empty just makes for a rough ride and reduced rear wheel traction, especially in the winter.
I asked Ford about this and their answer was to follow the Ford recommended values of course. I also figured if I lowered the rear tires to 65psi, the check tire pressure light woyld come on, which would annoy me.

My 2017 250 is the same.
I've found I can lower the tire pressures to 62 psi before it flags the light.
One caveat, if you go lower than 62, you have to go back up to 65 to put out the light. Then you can come back down a few pounds if you'd like. I'm running my rears at 64 psi empty. HUGE improvement in ride and in 8,000 miles, no adverse wearing.

[67L48]

Originally Posted by Trawlerphil

The Definitive Word on Tire Pressures

No, that doesn't exist.

[Cujo7240]

Originally Posted by 5picker

My 2017 250 is the same.
I've found I can lower the tire pressures to 62 psi before it flags the light.
One caveat, if you go lower than 62, you have to go back up to 65 to put out the light. Then you can come back down a few pounds if you'd like. I'm running my rears at 64 psi empty. HUGE improvement in ride and in 8,000 miles, no adverse wearing.

Thanks, I'll give that a try.

[Wilco]

Chevy recommends 60# front and 70# rear for my truck. This is conservative when comparing the rated axle weight of a fully loaded Silverado 2500 to the Goodyear load table list.

But most of the time the truck is empty and the high pressure degrades the ride comfort. I reduce the tire pressure to 55# front and rear. This improves the ride comfort tremendously and is still very conservative when I compare the unloaded truck weight to the load list. I could reduce it further but the low tire pressure warning comes on at 50#. I do increase the air pressure when I intend to haul anything.

[Mad Cow]

Originally Posted by Wilco

Chevy recommends 60# front and 70# rear for my truck. This is conservative when comparing the rated axle weight of a fully loaded Silverado 2500 to the Goodyear load table list.

But most of the time the truck is empty and the high pressure degrades the ride comfort. I reduce the tire pressure to 55# front and rear. This improves the ride comfort tremendously and is still very conservative when I compare the unloaded truck weight to the load list. I could reduce it further but the low tire pressure warning comes on at 50#. I do increase the air pressure when I intend to haul anything.

Yeah, I typically run the front at 55 and the rear at 50 on my 2500 unless I am loading things up. The TPMS has a fit every time I start the pickup. I dismiss it in the DIC and ignore the light on the dash. I didn't order TPMS and didn't want it. But it came with the pickup, so it is there. I just ignore it. I have gotten so good at ignoring the tire pressure light on the dash that I can't remember the last time I even noticed it. The angle of the steering wheel is perfect where I have it adjusted so that it covers it.

I found that running the lower inflation when empty actually improved mpg and reduced tire wear. I have become convinced that the higher pressures, when empty, lead to more wheel hop on the back end on rougher roads which negatively affects mpg and tire wear.

[Airdale]

Originally Posted by Macrosill

Unless I missed something, Michelin's definitive answer was to inflate the tire to the proper pressure based on the load.
That info is found in a tires load inflation chart.

Providing the pressure for the load is above vehicle manufacturer recommendations.

[Airdale]

Originally Posted by Cypressloser

Fact is, the tire inflation numbers on the door pillar become obsolete the moment you replace the OEM tires, Period. The vehicle manufacturer's recommendations for the OEM tires is always with the vehicle. When proper tire industry standards are applied, the load capacity for any replacement tires is to insure they provide the load capacity the OEM tires provided at the vehicle manufacturer's recommended cold inflation pressures. The new recommended cold inflation pressures can then be displayed on an auxiliary tire placard affixed next to the original. Find a tire retailer that has installers with that knowledge and you've found a good one. .
Some of the kids working at the tire shops don't even realize this and try to argue.

You did the right thing contacting Michelin and asking for a tire pressure chart, follow it as good as you can. If in doubt inflate the tires up to 5 psi higher, never lower.

The recommendation for 40 psi Front and 45 psi Rear seems odd, but maybe Michelin assumes a certain payload and wants you to add an extra 5 psi in the rear that works for these specific tires, IDK.
How this agrees with the 4x4 engaged, IDK. It may translate into excessive tire wear, wear in the transfer case and higher fuel consumption if you would leave it engaged on dry pavement but don't be afraid your truck will suddenly blow up and spontaneously combust.

See green.