Land Cruiser 200 - 285/65/18s

[TeCKis300]

Question is to our resident "expert" that's never been able to logically answer - Why does the LX570, effectively a higher base weight trim, ask for only a derived tire load pressure of 37PSI.

Thanks for the thumbsdown @gaijin

Please, do share. I'd like to think we're all reasonable and logical people.

 

[GrouchyTech]

Thanks for the thumbsdown @gaijin

Please, do share. I'd like to think we're all reasonable and logical people.

Could be the larger wheel size?

I settled on 37 PSI on my 285/65R18 Load E KO3s after using chalk to check the tread contact at a few different pressures from 33 to 42 PSI. If I need to tow or load up I’ll add a few pounds, but the projected center tread wear the chalk revealed at 42 PSI was NOT going to be OK. And the ride was s***, which is to be expected with those sidewalls at 42 PSI.

 

[TimCFJ40]

Thanks for the thumbsdown @gaijin

Please, do share. I'd like to think we're all reasonable and logical people.

Not looking for a Thumbs down also, but the tires/vehicle/suspension work together as a system. I'm sure somewhere along the line Toyota/Lexus engineers determined that the "system" as a whole on the LX would better work for the intended purpose with lower pressure compared to the "system" that is LC. It may very well just be that the LX purpose of posh-lux mall crawler demanded a softer smoother ride to satisfy the purpose, so the engineers at the Big T determined that a lower pressure (that still is over the Tire's pressure requirement to carry that load) would better suit that purpose.

I don't think the tires themselves care whether the 3-4 tons they are carrying are an LX, a LC, or a stack of 4 Miatas.

 

[bicycleagent003]

I think we can all safely experiment with PSI and decide for ourselves what feels good and works for our individual set ups. There's no oracle of objective truth for this. Enjoy your rig, run it the way you like, just do you, etc.
And thanks to everyone on this board who shares their knowledge and experience. That sharing is very valuable.

 

[open country]

Thanks for the thumbsdown @gaijin

Please, do share. I'd like to think we're all reasonable and logical people.

As far as I know, he just uses this calculator to give the needed pressure when changing tire size and type in order to maintain factory load rating. Easy enough to memorize the factory tire type for 200 series LX and LC. The link explains the need for there to be a difference versus the OEM "door jamb" pressures.

Tire Pressure Calculator - https://tiresize.com/pressure-calculator/

What is false about that logic?

 

[TimCFJ40]

As far as I know, he just uses this calculator to give the needed pressure when changing tire size and type in order to maintain factory load rating. Easy enough to memorize the factory tire type for 200 series LX and LC. The link explains the need for there to be a difference versus the OEM "door jamb" pressures.

Tire Pressure Calculator - https://tiresize.com/pressure-calculator/

What is false about that logic?

I think the longstanding disagreement is whether the LC could safely use LX pressures. The LX door Jamb pressures would result in "underinflated" tires on an LC even for the same size tire carrying the same exact load per the calculator above.

Calculating from the door jamb using a calculator as above is a great place to start and with stock or near stock setups, it should be about right for most people. Then you can adjust up or down for ride, contact patch etc. as long as you don't drop below the PSI required for your actual load as listed on the Tire Manufacturer's website for your particular tire/size or above the max PSI Cold on the tire sidewall.

 

[open country]

I think the longstanding disagreement is whether the LC could safely use LX pressures. The LX door Jamb pressures would result in "underinflated" tires on an LC even for the same size tire carrying the same exact load per the calculator above.

Calculating from the door jamb using a calculator as above is a great place to start and with stock or near stock setups, it should be about right for most people. Then you can adjust up or down for ride, contact patch etc. as long as you don't drop below the PSI required for your actual load as listed on the Tire Manufacturer's website for your particular tire/size or above the max PSI Cold on the tire sidewall.

I get that, but you'd use the factory LX tire and pressure spec for a new size on said LX, and the same for LC to LC. Maybe that's being crossed around somewhere but not by @gaijin who responds to folks changing sizes on the same vehicle.

Obviously there is some more tech and lots of personal preference in psi but the "recommended" CTIP isn't advertised as the one mandatory cold pressure for all people and situations, only a starting point as folks change setups. I've found it very helpful.

 

[hoser]

German engineers are a bit more particular about tire pressure. They'll give you RCITP for different # of passengers and recommended pressure for better fuel economy. Notice it's a Delta of up to 13psi for the same tire and tire position.

This might make @gaijin go berserk. But take 205/60R16 at 33/33 psi. Go to load inflation tables for new tire size (225/40R19) and it says you need 37psi now. But look more closely and German engineers say 37psi is too harsh , use 33psi instead (2nd red arrow).... the same pressure as the first tire.

 

[kortland]

Also on 285/65/18s Falken Wildpeak A/T3W. Zero rubbing, super smooth, great size. In fact, I'm likely going to upsize a little to 275/70/18s after these.

Do the 275/70/18’s rub with stock setup?