Recommended tire pressure for OEM tires? (1 Viewer)

[LCLXman]

I recently took possession of a 2017 LC, with Dunlop AT23 tires. Despite the door placard indicating 33 p.s.i. front and rear, the vehicle came with 40 p.s.i. in the front, and 38 p.s.i. in the rear. My first thought was you #$%% hillbillies at the dealership (we've had a few other issues). However, after running the recommended 33 p.s.i., I think the tires may be too soft, and the 40 p.s.i. might be closer to correct.
Do any of you have a p.s.i. recommendation for primarily highway/city driving?

 

[Utah200]

Just kick the tires until they feel right.

 

[Markuson]

Paging @gaijin -Aisle 11...

 

[gaijin]

I recently took possession of a 2017 LC, with Dunlop AT23 tires. Despite the door placard indicating 33 p.s.i. front and rear, the vehicle came with 40 p.s.i. in the front, and 38 p.s.i. in the rear. My first thought was you #$%% hillbillies at the dealership (we've had a few other issues). However, after running the recommended 33 p.s.i., I think the tires may be too soft, and the 40 p.s.i. might be closer to correct.
Do any of you have a p.s.i. recommendation for primarily highway/city driving?

If you are running the same type and size tires as on the door placard, and the placard says 33psi F/R, then you should be running 33psi F/R. Toyota really does know what they are doing when they print those placards.

HTH

Edit to add:

If your OEM tires are P285/60R18, then the recommended Cold Tire Inflation Pressure is 33psi Front/Rear. The tire pressure should be set when the tires are cold, prefereably after having sat overnight without being driven.

 

[LCLXman]

Just kick the tires until they feel right.

You must be one of those dealership hillbillies I spoke of....

 

[LCLXman]

If you are running the same type and size tires as on the door placard, and the placard says 33psi F/R, then you should be running 33psi F/R. Toyota really does know what they are doing when they print those placards.

HTH

Edit to add:

If your OEM tires are P285/60R18, then the recommended Cold Tire Inflation Pressure is 33psi Front/Rear. The tire pressure should be set when the tires are cold, prefereably after having sat overnight without being driven.

You make a good argument. Perhaps there is room for compromise at 35 p.s.i. I have to say the vehicle seems to corner and brake better *(that is for a Land Cruiser) with a little more air than recommended. Thanks so much for the replies.

 

[RobRed]

Did we forget driving conditions? Pressure is specific to the conditions of use - you cant just use 33 'cause its printed in the door placard.

Weather, weight, driving style and preferences all play here. Tires are designed to operate in a range of pressures to accommodate.

At 33psi cold set when up to operating temp the sidewall (AT23) is way too soft for my "TASTE" so 37.9 front 38.2 rear for me.

 

[LCLXman]

Did we forget driving conditions? Pressure is specific to the conditions of use - you cant just use 33 'cause its printed in the door placard.

Weather, weight, driving style and preferences all play here. Tires are designed to operate in a range of pressures to accommodate.

At 33psi cold set when up to operating temp the sidewall (AT23) is way too soft for my "TASTE" so 37.9 front 38.2 rear for me.

.2 and .9 ? You really have it down to a science. Based on what you posted, the 40 p.s.i. is not far from appropriate. I've owned an LX570, an LX470, a Raptor, and an H1 (civilian) Hummer, and never really felt the need to stray from the recommended tire pressure... until this Land Cruiser. You are right, the 33 p.s.i. is too soft even for daily pavement cruising. I also have to get used to what seems like a 5 minute 0-60 time. The quietness and build quality is truly first rate though.

 

[gaijin]

 

[TeCKis300]

There's certainly leeway to adjust pressure for personal preference and taste. Tire pressure is generally a compromise anyways between load capacity, comfort, and a myriad of other things.

I wouldn't go any below the recommended pressure from the manufacturer. But higher certainly is okay for less rolling resistance, stability, and tire rollover under aggressive cornering just to name a few. Just recognize that cold inflation pressure doesn't represent the actual tire pressure in use and it can go up quite dramatically. Too high may be a compromise too, obviously to ride quality, but also potentially to traction and treadwear with the center section bearing the burden of the weight.

 

[Markuson]

Couple things I've learned from gaijin:

Determining correct tire pressure is not about a "feel," a "hunch" or even past experience. It is about identifying the pressure that best matches/utilizes a specific tire's build characteristics with weight bearing needs.

These pressures exist at certain levels and remain at those identified levels of safety, performance and strength regardless of how it "feels" when you kick, corner, or bump.

So...until I figure out gaijin's math...my pressures are no longer left to my whims.

Deflation for larger footprint & traction at lower, off-road speeds are another question of holding a bead, etc., but if I've learned anything, it's that tire pressures are best derived by math that indicates optimal PSI for each tire spec, load and application...and those are specifically identifiable.

So gaijin...when you gonna make an online PSI tutorial?

 

[Yossarian]

Couple things I've learned from gaijin:

Determining correct tire pressure is not about a "feel," a "hunch" or even past experience. It is about identifying the pressure that best matches/utilizes a specific tire's build characteristics with weight bearing needs.

These pressures exist at certain levels and remain at those identified levels of safety, performance and strength regardless of how it "feels" when you kick, corner, or bump.

So...until I figure out gaijin's math...my pressures are no longer left to my whims.

Deflation for larger footprint & traction at lower, off-road speeds are another question of holding a bead, etc., but if I've learned anything, it's that tire pressures are best derived by math that indicates optimal PSI for each tire spec, load and application...and those are specifically identifiable.

So gaijin...when you gonna make an online PSI tutorial?

Agreed, there are no "alternate facts" here, science and engineering rule the day. BTW, gaijin has explained the calculations he uses and the science behind it in older threads. We are lucky to have his input.

 

[RobRed]

You guys crack me up. There is no one PSI setting to rule them all.

Engineering and Science are indeed fine and we should evaluate those parameters. I shouldn't have to explain that certain tire construction constraints exist and there will be out of range settings that could compromise safety.

In my case it's not a "hunch" or some alt fact. If you run AT23's at 33PSI cold they are terrible in steering feedback and the ride quality is awful on a 2017 LC. Please don't misunderstand the AT23 is just terrible in general but 33 on the street makes them worse.

It's great to have a guru in this field but his math cannot account for all the technical variables AND non-techincals. It's a nice starting point.

The OP asked and he got several opinions.

 

[Markuson]

You guys crack me up. There is no one PSI setting to rule them all.

Engineering and Science are indeed fine and we should evaluate those parameters. I shouldn't have to explain that certain tire construction constraints exist and there will be out of range settings that could compromise safety.

In my case it's not a "hunch" or some alt fact. If you run AT23's at 33PSI cold they are terrible in steering feedback and the ride quality is awful on a 2017 LC. Please don't misunderstand the AT23 is just terrible in general but 33 on the street makes them worse.

It's great to have a guru in this field but his math cannot account for all the technical variables AND non-techincals. It's a nice starting point.

The OP asked and he got several opinions.

Lots of factors matter. Just responding to a few comments. Not all. Exact pressure changes a little while driving no matter what due to temperatures, friction, sun, etc. Simply noting that there are identifiable pressures that most closely take advantage of each design and weight. Certainly there is wiggle room, or we'd all have to pull over every few minutes as temperatures and pressures went through their normal fluctuations. We don't do that. Just responding to the notion of playing around til it feels right...as a very iffy idea.

 

[Dan Higgins]

I run LT tires (KO2s) but I can say that after playing around with different PSI, I always end up back at the 42 that came from Gaigin's "math" (which is based on the tire industry spec I believe). And I must say that those KO2s at 42 feel great! Also, they generally increase by about 4 PSI while driving around and warming up. But it is 42 PSI cold for me. For the stock tires and my 285/60 R18 P-rated snow tires I use 33 per the door label. But I am a patient driver - I drive at or close to the speed limit, etc. And I treat the LC like a a big SUV. So my personal driving style

 

[Markuson]

I run LT tires (KO2s) but I can say that after playing around with different PSI, I always end up back at the 42 that came from Gaigin's "math" (which is based on the tire industry spec I believe). And I must say that those KO2s at 42 feel great! Also, they generally increase by about 4 PSI while driving around and warming up. But it is 42 PSI cold for me. For the stock tires and my 285/60 R18 P-rated snow tires I use 33 per the door label. But I am a patient driver - I drive at or close to the speed limit, etc. And I treat the LC like a a big SUV. So my personal driving style

Same experience here...at least on pavement. Aired down, all bets are off...