Tire Pressure recommendation (2 Viewers)

[K9LTW]

There are A LOT of factors why Toyota or any manufacturer to stipulate a higher tire pressure than required including fuel mileage, tire wear, handling, emergency handling.... lawsuits.... a lot of people are past GVWR. The TPMS doesn't not alert unless a certain threshold below recommended tire pressure. That's probably a factor too.

There's a range of pressure that is considered safe, none exceeding maximum pressure listed on the sidewall. All choices have compromises. There's optimal and there is acceptable. I'd even say the manufacturer's pressure listed on the TIP is less than optimal when loaded to GVWR. Should probably be 5-10psi higher than stated

There's already a buffer built in to the tire's load rating with a static load. The difference between dynamic load and static load is even greater when going off road in the sand or desert. Members here, including myself are running ~20psi for hundreds (some thousands) of miles over washboard and bumpy terrain without issue.... and with more weight. This is not the same as driving on the road but it is a testament to the strength of these LT tires. Running 37 psi on washboard roads would be more dangerous than 20 psi. Don't believe me? Try it.

Not sure what your bone to pick here, but no one's talking about airing down on washboard roads. @gaijin is simply quoting pressures...correctly...for IMPROVED roads (i.e. highways). We're not talking slower speeds and airing down. Hell I've run on the road for 10 miles between dirt running only 20 under my RAM. But I went slowly, didn't turn aggressively and got out of anyone's way that happened by.

 

[hoser]

I have no bone to pick with @gaijin i only question his repeated statements about the lowest safe pressure you can go on any vehicle, of any weight, with an LT Metric tire is 35psi. Where is that stated and what is the reason? He doesn’t know where he read it. It’s not explicitly stated in the TRA “bible.”

So a 2,000 lb Suzuki Samurai on LT Metric tires has to run 35+ psi on the road or else it’ll become a death trap?

 

[gaijin]

I have no bone to pick with @gaijin i only question his repeated statements about the lowest safe pressure you can go on any vehicle, of any weight, with an LT Metric tire is 35psi. Where is that stated and what is the reason? He doesn’t know where he read it. It’s not explicitly stated in the TRA “bible.”

So a 2,000 lb Suzuki Samurai on LT Metric tires has to run 35+ psi on the road or else it’ll become a death trap?

Let's try this:

Why 35 PSI Is the Minimum in TRA Tables​

• Structural Integrity: Below 35 psi, LT-Metric tires may not maintain sufficient sidewall stiffness, risking excessive flexing, heat buildup, and potential failure.
• Load-Carrying Capacity: 35 psi is the lowest pressure at which LT tires can safely carry the minimum rated load for their size. Dropping below this compromises the load index and violates FMVSS No. 110 compliance.
• Industry Consensus: TRA, ETRTO, and JATMA harmonize standards to ensure global consistency. 35 psi is the agreed-upon baseline for LT-Metric tires across these organizations.

Was a Destructive Test Performed?​

Yes—though not publicly detailed in the tables, destructive testing is a cornerstone of tire validation. Here's how it typically works:

• Step 1: Load vs. Pressure Testing Tires are inflated to various pressures and subjected to increasing loads until deformation or failure occurs. This helps define the safe operating envelope.
• Step 2: High-Speed and Endurance Tests Tires are run at high speeds under load to simulate real-world stress. Failures at low pressures (e.g., below 35 psi) often involve sidewall collapse or tread separation.
• Step 3: Regulatory Compliance FMVSS No. 109 and No. 110 require tires to pass endurance and high-speed tests at specified pressures. These tests indirectly validate the lower pressure limit.

While the TRA Load Inflation Tables don’t cite specific destructive test data, the 35 psi floor is a product of these rigorous evaluations. It’s not just a conservative guess—it’s a line drawn from empirical testing and safety margins.

HTH

 

[hoser]

No, that doesn't work out. I've used AI enough to know that I can tailor the prompts to get the answers I want. I even checked the FMVSS sources for minimum pressure test and there's nothing relevant there. No need to continue on....
---------

Not sure what your bone to pick here, but no one's talking about airing down on washboard roads. @gaijin is simply quoting pressures...correctly...for IMPROVED roads (i.e. highways). We're not talking slower speeds and airing down. Hell I've run on the road for 10 miles between dirt running only 20 under my RAM. But I went slowly, didn't turn aggressively and got out of anyone's way that happened by.

Most trucks do 45-50 mph on the flat straights in the desert. The performance trucks go faster. You have to go that fast to get up on "plane" otherwise your teeth will fall out. My point was, it is more rigorous than the improved road test.

 

[gaijin]

No, that doesn't work out. I've used AI enough to know that I can tailor the prompts to get the answers I want. I even checked the FMVSS sources for minimum pressure test and there's nothing relevant there. No need to continue on....
---------
View attachment 4001070


Most trucks do 45-50 mph on the flat straights in the desert. The performance trucks go faster. You have to go that fast to get up on "plane" otherwise your teeth will fall out. My point was, it is more rigorous than the improved road test.

As we should all be aware, AI output is only as good as its input. That is why it is important to evaluate the output carefully before assigning any degree of confidence to the content.

In the case of your AI output, it is not difficult to see that the content is based on a flawed input based on the very first sentence:

"The Tire and Rim Association (TRA) tables, particularly for LT-Metric tires, specify a minimum inflation pressure of 25 PSI for several reasons..."

That is an untrue statement. The TRA tables for LT-Metric tires specify a minimum pressure of 35 PSI.

So I agree with your concession, "No need to carry on..."

HTH

 

[riffman12]

quick - someone try and tie politics into national tire safety regulations and let's really see this thing crack off.

 

[TeCKis300]

Let's try this:

Why 35 PSI Is the Minimum in TRA Tables​

• Structural Integrity: Below 35 psi, LT-Metric tires may not maintain sufficient sidewall stiffness, risking excessive flexing, heat buildup, and potential failure.
• Load-Carrying Capacity: 35 psi is the lowest pressure at which LT tires can safely carry the minimum rated load for their size. Dropping below this compromises the load index and violates FMVSS No. 110 compliance.
• Industry Consensus: TRA, ETRTO, and JATMA harmonize standards to ensure global consistency. 35 psi is the agreed-upon baseline for LT-Metric tires across these organizations.

This is bunk.

There is no minimum implied just because a reference (not bible, not requirements) just so happens to focus on a certain range. In the real world, there is a continuum of useful inflation pressures below 35 depending on application and use case. I have buddies using matching LT tires on their lightweight trailers, running on the highway, with much less than 35 PSI.

Off-road, I've likewise run hundreds of miles at at lower inflation pressures and high speeds. Cross checking temps and pressure rise, and still well within safe ranges.

Of course, discretion should be used and load tables can be useful to cross check, but the engineering world is full of trades and compromises that do not live in a strict 1 dimension box.

 

[nor_cal_cyclist]

Just pulled my BBS rims and spacers....would like recommended pressure for BFG KO3's in 285/75-R17 Load Range E

 

[gaijin]

Just pulled my BBS rims and spacers....would like recommended pressure for BFG KO3's in 285/75-R17 Load Range E

The RCTIP (Recommended Cold* Tire Inflation Pressure) for those LT285/75R17/E 128/125S tires on your LC200 is 37psi Front/Rear.

*According to Toyota:

Tire Pressure vs. Tire Temperature

Tire temperature is dependent on “cold” tire pressure, driving distance and speed, ambient temperature and road surface temperature. As the temperature of the tire changes, air in the tire expands and contracts, changing the tire’s air pressure. The cold tire pressure for all Toyota models will vary and will need to be adjusted accordingly.

“Cold” tire pressure, as shown on the tire pressure label on our vehicles, is generally considered to be the pressure in a tire that has not been driven in the past 4 hours and has been parked outdoors.

HTH

 

[nor_cal_cyclist]

Thank you!!!