Need help regarding PSI for new tires land cruiser 1958

[LC250ownerx]

Hello, I just got the LT245/70R18 BF goodrich KO3s for the 1958. They have a D load rating or 115/112 (I'm not technical). Anyone else have these and what PSI are you running them at? Any help would be greatly appreciated. I saw someone running them at 40 so that is what I have been doing but calculations indicate, I believe, it should be higher.

 

[PDPete]

Hello, I just got the LT245/70R18 BF goodrich KO3s for the 1958. They have a D load rating or 115/112 (I'm not technical). Anyone else have these and what PSI are you running them at? Any help would be greatly appreciated. I saw someone running them at 40 so that is what I have been doing but calculations indicate, I believe, it should be higher.

It was probably my post that you saw, so this likely isn't helping much, but it's the type of thing that seems like it should be easy, yet can make your brain hurt if you analyze it too much...

If you use the 33 psi recommendation on the door sticker for SL tires and extrapolate from there, then that would equate to around 45 psi for the KO3's with a D load range.

If you go strictly by vehicle weight, I believe that you should be able safely to go lower than that, however. Based on other threads I've come across, it seems that ~2700 lbs per axle is a decent estimate of load...

LT245/70R18 Tire Pressure

Discover the load limits at various inflation pressures for LT245/70R18 tires to ensure optimal tire performance and a safe drive.

tirepressure.com

I've had mine at 40 psi and haven't had any issues and the ride is decent...felt a little too stiff when I initially had them at 45.

 

[LC250ownerx]

Thank you so much for your response.

 

[RideWithYanu]

There’s no universally “correct” PSI - it all depends on how you use your vehicle and what tradeoffs you’re willing to make.

If you’re aiming for fuel efficiency and tire longevity on pavement, you’ll want to run higher pressures, typically in the 38-42 PSI range (or near the tire’s max spec, as long as it’s within what your vehicle can handle). The benefit here is reduced rolling resistance, which can improve MPG slightly and extend tread life under highway conditions. The downside is a stiffer ride, increased road noise, and more wear and tear on suspension components. You’ll also have a smaller contact patch, which compromises grip in low-traction environments - not ideal for snow, sand, or other off-road use.

If ride comfort is your goal, dropping down to the 32–35 PSI range tends to offer the best balance for daily driving. This pressure softens the ride and improves tire compliance over rough surfaces, which can also enhance handling on uneven pavement. The tradeoff is slightly reduced fuel efficiency and potentially a bit more tread wear over time if the tires are underinflated relative to load - but for most drivers, the comfort gain is worth it.

If off-road traction is the priority, you’ll want to air down significantly - anywhere from 5 to 25 PSI, depending on the terrain, your wheels, and your experience with driving with very low pressure (or your willingness to reseal in a spare or rebrand a tire). Lowering pressure increases the tire’s contact patch and allows the sidewalls to flex, which dramatically improves grip on rock, sand, snow, and mud. The downside is reduced sidewall integrity and a higher risk of de-beading, especially without beadlock wheels or tires with bead retention technology like Bead Grip. It also increases sidewall wear and heat buildup if used for extended driving at speed, so it’s strictly for off-pavement use at low speed.

 

[Roonie]

I have E load range and had it up in the 40's psi and way too stiff. Now I am at 35 psi and it ride nice again.

 

[TimHerald]

I have E-laod 285/75/r18's. The tire shop set them at 40. It rides pretty well. Would I be better off dropping it, or just before off-roading? I had my stock 265's at 33 per the door sticker.

 

[NoMe cruiser]

I personally don’t run any tire more than 40 psi. I don’t haul heavy loads and I am frequently on gravel roads. I think of tires like a balloon, high pressure balloon is easier to pop than a low pressure balloon.
Every tire and person will have a happy medium of psi to run at. I usually run 30-35 psi. That offers me decent comfort and mpg on the road without being too high for gravel roads. I never “air down” when off roading. My type of 4wd use is usually in short distances like crossing a wash out, beaver dam, or snow drift. Maybe an occasional slippery slope. Unless you “air down” to less than 10 psi there is no significant increase in traction with most tires. And then when running low psi like that you run the risk of breaking off the bead. People that rock climb all day long are obviously running low psi and are probably prepared to get a tire back on the bead.

 

[RideWithYanu]

Running E-load tires, my routine is 35 PSI on the road and a maximum of 15 PSI if I’m leaving tarmac for more than an hour. Makes such a big difference in ride comfort and traction. I go down to 5-8 if I’m getting into a really low traction scenario (snow, mud, or crawling up rocky paths).

 

[PDPete]

There’s no universally “correct” PSI - it all depends on how you use your vehicle and what tradeoffs you’re willing to make.

If you’re aiming for fuel efficiency and tire longevity on pavement, you’ll want to run higher pressures, typically in the 38-42 PSI range (or near the tire’s max spec, as long as it’s within what your vehicle can handle). The benefit here is reduced rolling resistance, which can improve MPG slightly and extend tread life under highway conditions. The downside is a stiffer ride, increased road noise, and more wear and tear on suspension components. You’ll also have a smaller contact patch, which compromises grip in low-traction environments - not ideal for snow, sand, or other off-road use.

If ride comfort is your goal, dropping down to the 32–35 PSI range tends to offer the best balance for daily driving. This pressure softens the ride and improves tire compliance over rough surfaces, which can also enhance handling on uneven pavement. The tradeoff is slightly reduced fuel efficiency and potentially a bit more tread wear over time if the tires are underinflated relative to load - but for most drivers, the comfort gain is worth it.

If off-road traction is the priority, you’ll want to air down significantly - anywhere from 5 to 25 PSI, depending on the terrain, your wheels, and your experience with driving with very low pressure (or your willingness to reseal in a spare or rebrand a tire). Lowering pressure increases the tire’s contact patch and allows the sidewalls to flex, which dramatically improves grip on rock, sand, snow, and mud. The downside is reduced sidewall integrity and a higher risk of de-beading, especially without beadlock wheels or tires with bead retention technology like Bead Grip. It also increases sidewall wear and heat buildup if used for extended driving at speed, so it’s strictly for off-pavement use at low speed.

This is absolutely true for "Standard load" or "SL" tires...once you get into light-truck rated tires with 'C' through 'E' load ranges, those numbers tend to go up...this is why if you swap out the stock tires for something more heavy duty and/or a different size, you can't necessarily just go by the door sticker anymore...

I have E load range and had it up in the 40's psi and way too stiff. Now I am at 35 psi and it ride nice again.

I have E-laod 285/75/r18's. The tire shop set them at 40. It rides pretty well. Would I be better off dropping it, or just before off-roading? I had my stock 265's at 33 per the door sticker.

I personally don’t run any tire more than 40 psi. I don’t haul heavy loads and I am frequently on gravel roads. I think of tires like a balloon, high pressure balloon is easier to pop than a low pressure balloon.
Every tire and person will have a happy medium of psi to run at. I usually run 30-35 psi. That offers me decent comfort and mpg on the road without being too high for gravel roads. I never “air down” when off roading. My type of 4wd use is usually in short distances like crossing a wash out, beaver dam, or snow drift. Maybe an occasional slippery slope. Unless you “air down” to less than 10 psi there is no significant increase in traction with most tires. And then when running low psi like that you run the risk of breaking off the bead. People that rock climb all day long are obviously running low psi and are probably prepared to get a tire back on the bead.

What OP needs to keep in mind, along with others, is that the tire pressue/weight recommendation changes depending on the size and dimensions of the tire. This is why I linked to the chart in my previous post above for the exact size that OP has (245/70R18). Wider tires tend have lower psi recommendations than the skinnier 245s at the same max weight. (And while that chart doesn't have the D load range specified, it would be max at the 2680 lbs @ 65 psi column)

 

[RideWithYanu]

This is absolutely true for "Standard load" or "SL" tires...once you get into light-truck rated tires with 'C' through 'E' load ranges, those numbers tend to go up...this is why if you swap out the stock tires for something more heavy duty and/or a different size, you can't necessarily just go by the door sticker anymore...






What OP needs to keep in mind, along with others, is that the tire pressue/weight recommendation changes depending on the size and dimensions of the tire. This is why I linked to the chart in my previous post above for the exact size that OP has (245/70R18). Wider tires tend have lower psi recommendations than the skinnier 245s at the same max weight. (And while that chart doesn't have the D load range specified, it would be max at the 2680 lbs @ 65 psi column)

Everything in my post you quoted applies to D and E (what I use) load tires.

 

[Blue Bear]

Hello, I just got the LT245/70R18 BF goodrich KO3s for the 1958. They have a D load rating or 115/112 (I'm not technical). Anyone else have these and what PSI are you running them at? Any help would be greatly appreciated. I saw someone running them at 40 so that is what I have been doing but calculations indicate, I believe, it should be higher.

The load estimate is based on Toyota's choice of OEM tires and their load specifications. In other words, you can look at the load rating on the OEM tire and then look up the load for that rating. I originally posted this info in my post about Falken Wildpeak AT4Ws, but the ETRTO tables are the industry standard.

1. Current Load Index is 112. According to Falken, an Index of 112 at 33 psi is a load of 2469 lbs. Evidently metric tires include a 10% overage when used on an SUV. So, the equivalent load I need for my tires is 2469/1.1 = 2104 lbs. Note that the link for the load table is the ETRTO load inflation table.

2. Based on the load inflation table, the LT245/70R18 the load at 40 psi is 1920 lbs, the load at 45 psi is 2085 lbs, and the load at 50 psi is 2270 lbs. So, 45 psi gives you a load of 2085 lbs and 46 psi gives you a load of 2122 lbs. I'd probably try 45 psi and then do a chalk test to check the inflation.

The load table for D and E load tires is the same (they are both LT tires). The primary difference you'll see noted in the table is that the maximum load for a D load is less than an E load.

Keep in mind that these are based on the maximum load for the tires. You may be able to run lower pressures in your daily use/load, but expect the tire wear to be uneven. Running too low a pressure at higher speeds can also increase the heat generated in the tire and lead to premature failure.