Toyo OpenCountry AT3 Experience? (2 Viewers)

[lx200inAR]

Hey gaijin,

ive followed some of your posts and I know you’re well respected here im not trying to knock you or anything but its impossible for 26 psi to be the correct pressure for 200/570. Thats basically flat.

i can post a photo if needed but I recommend anyone running P metric to go 36-38.

Im curious how you are calculating the pressure.

If you follow his posts, you should see that he regularly posts the method taken from Toyo: Guidelines for the Application of Load and Inflation Tables
Lexus recommends a pretty low RCTIP, i assume to work in concert with the AHC suspension. The P285/70r17 tires have a higher load index than the stock tires on a LX, so it would only make sense that the tires would require less pressure than the stock 285/50R20 to maintain the same load characteristics.

P285/70r17 @ 26PSI have load rating of 2480
P285/50r20 @ 35PSI have load rating of 2403 (Lexus recommendation is 33PSI)

 

[NYC570]

Are you running this tire?

Yes, I'm running it at around 26 PSI according to the toyo tables. @gaijin has linked the tables in the tire pressure recommendation thread. I also thought that it was a bit low, but it's what's recommended.

 

[gaijin]

Hey gaijin,

ive followed some of your posts and I know you’re well respected here im not trying to knock you or anything but its impossible for 26 psi to be the correct pressure for 200/570. Thats basically flat.

i can post a photo if needed but I recommend anyone running P metric to go 36-38.

Im curious how you are calculating the pressure.

If you have followed even some of my posts, you should be familiar with the industry standard methodology I use to pass on the RCTIP.

I'm curious how you arrive at your recommendation for "anyone" running "P metric" to "go 36-38" - can you detail your methodology and the industry sources you use to validate it?

If you are correct, then wow, Toyota must be really stupid! Isn't the RCTIP (located on the TIP (Tire Information Placard)) for the stock P285/50R20 tires 33psi? And for the LC200, the RCTIP on the TIP for the stock P285/60R18 is also 33psi. So... it appears that your overbroad recommendation is incorrect and unfounded.

You are free to overinflate your tires - your vehicle, your choice; but you would be unnecessarily subjecting yourself to the myriad of adverse/detrimental effects caused by overinflation (I've posted about this, so you may have already seen them, but you can Google it).

If you are curious about the science behind the RCTIP I gave you, feel free to read this excellent monograph on the subject published by Toyo Tires which explains the TRA (Tire and Rim Association) tables and how to use them: Guidelines for the Application of Load and Inflation Tables

You will find that for your P285/70R17 117T SL tires on your LX570 the RCTIP is 26psi F/R. Not impossible, just correct.

After reading Toyo's Guidelines, and trying the calculations for yourself, if you have any questions please feel free to post them up.

HTH

 

[AnyMal]

If you have followed even some of my posts, you should be familiar with the industry standard methodology I use to pass on the RCTIP.

I'm curious how you arrive at your recommendation for "anyone" running "P metric" to "go 36-38" - can you detail your methodology and the industry sources you use to validate it?

If you are correct, then wow, Toyota must be really stupid! Isn't the RCTIP (located on the TIP (Tire Information Placard)) for the stock P285/50R20 tires 33psi? And for the LC200, the RCTIP on the TIP for the stock P285/60R18 is also 33psi. So... it appears that your overbroad recommendation is incorrect and unfounded.

You are free to overinflate your tires - your vehicle, your choice; but you would be unnecessarily subjecting yourself to the myriad of adverse/detrimental effects caused by overinflation (I've posted about this, so you may have already seen them, but you can Google it).

If you are curious about the science behind the RCTIP I gave you, feel free to read this excellent monograph on the subject published by Toyo Tires which explains the TRA (Tire and Rim Association) tables and how to use them: Guidelines for the Application of Load and Inflation Tables

You will find that for your P285/70R17 117T SL tires on your LX570 the RCTIP is 26psi F/R. Not impossible, just correct.

After reading Toyo's Guidelines, and trying the calculations for yourself, if you have any questions please feel free to post them up.

HTH

I understand that, and please you dont have to get defensive. I own this car and tire and have done rigorous testing to come to my conclusion.

Recommended tire pressure is NOT just a function of load rating. Its extremely ignorant to assume that. That is mostly a safety and operational parameter. Im familiar with toyos table as well and to call that scientific is well a huge overstatement.
If you want science you have got to get into racing world and see the plethora of characteristics they design for.

There is much more that goes into the choices engineers make for tire size and their respective pressure. Your tire must conform to the road, handle sidewall flexion, have the right balance of give and bounce, and also should not increase in PSI more than 10% once at temp as a rule of thumb.

If you are starting at 26 PSI, im curious where that is ending up, but I guarantee you that the tire is heating up WAY too much and adding way more than 3 PSI as a result of heat at operating temp.

Not only that if you did a chalk test im sure that you would be wearing out your outer tread.

Im gonna be honest with you, at 26 PSI the car drives and handles like s***, the tires are basically flat, and the suspension is not functioning like it should. Its dangerous if you asked me. But feel free to underinflate your tires.

I would also like to add that there is no way you are getting close to factory MPG at 26 PSI.

NYC570 please post a picture of 26 PSI cold so i dont have to go through the trouble of pulling out the pump.
Have you ever tried going up in pressure?

 

[04UZJ100]

When talking tires, get out the

 

[NYC570]

I understand that, and please you dont have to get defensive. I own this car and tire and have done rigorous testing to come to my conclusion.

Recommended tire pressure is NOT just a function of load rating. Its extremely ignorant to assume that. That is mostly a safety and operational parameter. Im familiar with toyos table as well and to call that scientific is well a huge overstatement.
If you want science you have got to get into racing world and see the plethora of characteristics they design for.

There is much more that goes into the choices engineers make for tire size and their respective pressure. Your tire must conform to the road, handle sidewall flexion, have the right balance of give and bounce, and also should not increase in PSI more than 10% once at temp as a rule of thumb.

If you are starting at 26 PSI, im curious where that is ending up, but I guarantee you that the tire is heating up WAY too much and adding way more than 3 PSI as a result of heat at operating temp.

Not only that if you did a chalk test im sure that you would be wearing out your outer tread.

Im gonna be honest with you, at 26 PSI the car drives and handles like s***, the tires are basically flat, and the suspension is not functioning like it should. Its dangerous if you asked me. But feel free to underinflate your tires.

I would also like to add that there is no way you are getting close to factory MPG at 26 PSI.

NYC570 please post a picture of 26 PSI cold so i dont have to go through the trouble of pulling out the pump.
Have you ever tried going up in pressure?

Yes and it was a bit too bouncy. I'll do chalk test whenever I have time to see what the best contact patch / tire pressure is for mine. At 26 PSI, my tires have a bit of a bulge, but they're far from flat. These tires do get to their max load rating at 35psi, so anything above that is way too high.

 

[lx200inAR]

I understand that, and please you dont have to get defensive. I own this car and tire and have done rigorous testing to come to my conclusion.

Recommended tire pressure is NOT just a function of load rating. Its extremely ignorant to assume that. That is mostly a safety and operational parameter. Im familiar with toyos table as well and to call that scientific is well a huge overstatement.
If you want science you have got to get into racing world and see the plethora of characteristics they design for.

There is much more that goes into the choices engineers make for tire size and their respective pressure. Your tire must conform to the road, handle sidewall flexion, have the right balance of give and bounce, and also should not increase in PSI more than 10% once at temp as a rule of thumb.

If you are starting at 26 PSI, im curious where that is ending up, but I guarantee you that the tire is heating up WAY too much and adding way more than 3 PSI as a result of heat at operating temp.

Not only that if you did a chalk test im sure that you would be wearing out your outer tread.

Im gonna be honest with you, at 26 PSI the car drives and handles like s***, the tires are basically flat, and the suspension is not functioning like it should. Its dangerous if you asked me. But feel free to underinflate your tires.

I would also like to add that there is no way you are getting close to factory MPG at 26 PSI.

NYC570 please post a picture of 26 PSI cold so i dont have to go through the trouble of pulling out the pump.
Have you ever tried going up in pressure?

I believe the expectation is that Toyota already did all the testing/math you are referring to and that’s why the RCTIP isn’t a function of GVWR, with the exception of maintaining safety limits. In fact the LX570 and LC200 have very similar GVWRs yet have different RCTIP, which has been covered here ad nauseam.

 

[AnyMal]

Yes and it was a bit too bouncy. I'll do chalk test whenever I have time to see what the best contact patch / tire pressure is for mine. At 26 PSI, my tires have a bit of a bulge, but they're far from flat. These tires do get to their max load rating at 35psi, so anything above that is way too high.

At 26 PSI, you are destroying your suspensions rebound rate.
At least go to 32.Ive driven at 32, and its a mushy mess for me.
What pressure is your tire ending up after full temp?

 

[AnyMal]

I believe the expectation is that Toyota already did all the testing/math you are referring to and that’s why the RCTIP isn’t a function of GVWR, with the exception of maintaining safety limits. In fact the LX570 and LC200 have very similar GVWRs yet have different RCTIP, which has been covered here ad nauseam.

Well the LX is heavier than the LC so i wouldn’t necessarily go off that, they run completely different wheel/tires as well. They should indeed be different.
Your talking 20-21” on the LX with little sidewall.

I want to add that my point here is that load rating equivalent is not a good way to determine correct inflation pressure. It is just a tool to match or exceed what is required for the weight of the vehicle. Sure you can match the chart, but when you grossly oversize a tire like from a 20 ratio to a 70, you don't just blindly go off of load matching...

 

[Chewbacca]

Well the LX is a full 1,000 lbs heavier than the LC so i wouldn’t necessarily go off that, they run completely different wheel/tires as well. They should indeed be different.
Your talking 20-21” on the LX with little sidewall.

More like 200# heavier.

 

[AnyMal]

More like 200# heavier.

You’re right sorry

 

[NYC570]

At 26 PSI, you are destroying your suspensions rebound rate.
At least go to 32.Ive driven at 32, and its a mushy mess for me.
What pressure is your tire ending up after full temp?

You must have really nice roads where you live.

 

[TeCKis300]

Well the LX is heavier than the LC so i wouldn’t necessarily go off that, they run completely different wheel/tires as well. They should indeed be different.
Your talking 20-21” on the LX with little sidewall.

I want to add that my point here is that load rating equivalent is not a good way to determine correct inflation pressure. It is just a tool to match or exceed what is required for the weight of the vehicle. Sure you can match the chart, but when you grossly oversize a tire like from a 20 ratio to a 70, you don't just blindly go off of load matching...

I agree with our in house guru that load rating is a good guideline, but only as a start to determining inflation pressure. To your point, it absolutely is not the singular tool or criteria that many have been lead to believe as gospel. Good on you to comprehending that.

I've yet to get around to a thorough write-up as it's complex. Will get around to it one day.

 

[Madtiger]

I agree with our in house guru that load rating is a good guideline, but only as a start to determining inflation pressure. To your point, it absolutely is not the singular tool or criteria that many have been lead to believe as gospel. Good on you to comprehending that.

I've yet to get around to a thorough write-up as it's complex. Will get around to it one day.

Oh please no. No more long write up from you with false info.

 

[TeCKis300]

Oh please no. No more long write up from you with false info.

Just for you mad...

 

[hickuptruck]

For anyone interested, the product manager of the toyo At3 tire, and also a 200 series land cruiser owner which was used during production and testing of the tire, goes into detail the RCTIP tables that Gaijin many recommendations on this board has posted up. Good video highlighting/marketing the tire and also RCTIP tables.

 

[AnyMal]

You must have really nice roads where you live.

Not necessarily no. I find the tires soft enough to stay in standard damping actually most of the time with the occasional comfort mode.
My ride is much, much more supple than the 21” package my car came with. I cant imagine seriously driving around at 26 PSI though. Your sidewall is crumpling on turns, its just not stiff enough in this P metric at this size. Its extremely dangerous. What are you getting like 8 MPG? What is the tire increasing to at operating temp? Its putting way too much resistance on it and im sure its jumping quite a bit with all that heat.
Up your tire pressure man.

 

[bloc]

It is just a tool to match or exceed what is required for the weight of the vehicle.

And yet the entire point of the load table is to define the minimum cold pressure to maintain a given load at the speed rating of the tire.. without overheating and destroying the tire.

So maybe we shouldn’t say the load table specified pressure will cause the tire to overheat?

Fair to have other critiques of the method but by definition that isn’t a good one.

 

[gaijin]

For anyone interested, the product manager of the toyo At3 tire, and also a 200 series land cruiser owner which was used during production and testing of the tire, goes into detail the RCTIP tables that Gaijin many recommendations on this board has posted up. Good video highlighting/marketing the tire and also RCTIP tables.

Excellent video - thanks for posting it!

Great info about how to use the TRA tables to determine RCTIP. In the video, desired values are rounded up to the nearest published value in the tables. When I do my calcs, I interpolate to the nearest whole psi value that covers the required Load Limit; but certainly the rounding up shown in the video is safe.

 

[amunsey]

Following the YouTube video posted by hickuptruck regarding the Toyo inflation tables, here is what I came up with regarding my tire replacement air pressures:

2011 Lexus LX570

OE Tire Size: P285/50R20
Factory Recommended Pressure: 33PSI

Replacement Tire: LT285/55R20
New Pressure: 45PSI (calculation below)

For the original tire, the load capacity at 35PSI (33PSI isnt listed on the tables) is 2403lbs according to the Rim TIre Assocation Table.

Since the car was originally equipped with a P metric tire and I switched it to an LT tire, I divide the load capacity by 1.10.

2403/1.10 = 2184

Referencing the Rim Tire Association Table, I go to the LT285/55R20 section and look for a PSI that meets or exceeds the 2184lbs load capacity.

The table shows that the first pressure that meets this capacity is 45PSI. At 45PSI, the load capacity is 2,205lbs.

This would make sense at my tire installer filled all 4 new tires to 45PSI. If anyone sees any errors with this calculation, please let me know.