Plug Guy

After a few weeks of driving the beast, I finally checked everything out a few weekends ago.

The bigger problem I faced was left pull upon braking, but it's very subtle. Dealer is checking alignment next week, brakes already checked fine, and no sensor issues.

When I checked the tires (post delivery, never checked until this time), I found 38 psi in each. Door Jamb sticker shows 30 psi suggested.

I know they likely overinflate for the boatride over and to reduce flat-spotting, but wouldn't you think the pre-delivery inspection would have checked for proper inflation?

Anyway, I found the vehicle ran fine at those pressures, and was uncertain about dropping it 8 lbs per tire, so I ran it down to 35 for a few days.

What are your pressures and where is the comfort level for most?

TIA

jim256

After 6 months of testing and reading the various boards, 32 works best for me. I have the Goodyears with the 260 treadwear rating, so I'm not expecting much with them, but so far with 4k miles, no unusual wear patterns. I'll also occasionally sense what might be a left pull at slow braking, so let us know what they say. I have not yet been back for the first service but will do it in March. I'm happy with mine, hope you will be, too.

RandyL712

The tires themselves are marked with a maximum recommended pressure, which I'm sure you're under at 35 PSI - but I'd recommend using Lexus' guideline of 30. I'm no expert, but every single time this has been asked in all of the car magazines, they say "Go with the vehicle manufacturer - they designed the vehicle to run on those tires at that PSI"

oldcajun

Apparently one of the things that get missed in pre-delivery service is setting tire pressures. I had a tire problem (nail) and during repair, the tire place checked pressure in the other 3 tires and all were over 40 psi. This was at 3500 miles and no one else had touched the car. The service manager at the dealer accepted responsibility and said he would make this a point to check in future deliveries. On my next new car, I will have the tire pressure checked before driving off.

I have been running 32 psi since and like the way the car drives. It also allows a little margin for air loss without going below a reasonable pressure.

Steve

MadloR

Tires talk, believe it or not. If you don't have experience with this, take your vehicle to a qualified alignment shop, dealer, mechanic etc and they can "feel" the tire and see if there is any unusual tire wear characteristics. Even after 3k miles, a person with experience can see if the tire is starting to cup, wear unevenly, overinflation or underinflation wear etc...

Of course, it is important to make sure the vehicle is properly aligned, that being said, we know that higher tire pressures will give less rolling resistance. Even though Lexus recommends 30psi, I have been reading from many posters, that they are experiencing under inflation wear (the outside edges wearing away quicker than the center of the contact patch).

I plan on running 36psi in my tires, and anywhere from 5-7 psi more this month (we get temperatures in the -25 - 30 f) due to the extreme cold weather. I will monitor the wear after about 2-3k miles and see if there are any peculiarities. Remember, each vehicle is different in how it is driven and how well the vehicle is aligned.

Cheers,

MadloR

joedaddy1

iTrader: (1)

33~35 seem to work for me

Ron Simon

I just bought a 400h with 18 in wheels. When I got home I checked the tire pressure and all four on the ground were between 38 and 40psi. I called the dealer and checked with the service dept. I was told that 38 to 40psi was correct and to ignore the recommended 30psi. It seems to ride well at that pressure. Time will tell.

katzjamr

all lexus 400h are shipped from the factory with 40psi to eliminate flat spots on the tires during storage. most dealers will not leave the tires at that pressure, and in my opinon your dealer is either lazy, or covering up the fact that they didnt check the pressure during what passes for their dealer prep. This is the number one overlooked dealer issue when shipping out a 400h. My dealer sets the goodyears at 34 psi, i have driven them with 40 to and to me the ride is harsh and handling worse. just my opinion. i do think they should be set slightly higher than what is reccomended on the door.

tod071

35psi from the dealer here. But, I inflated them to 40psi and have been ever since. Better gas mileage and I like the "bouncy" feel vs "bumpy".

joedaddy1

iTrader: (1)

don't u get more "bumpy" feel with the 40psi?
35psi = more sidewall flex = bounce
40psi = stiff sidewalls = more punch/pound to ur butt

tod071

I've heard that and have been told that by many people. But, from my experience,
35psi = more grip, meaning larger area surface meeting the road, feel more bumps. less air, less bounce

40 = less grip, but less surface on the road, less bumps

Not the best explanation, but basically, when I lower the psi, I feel more bumps and potholes. Higher the psi, less potholes and smoother ride.

MadloR

Technically speaking, higher air pressure gives less of a smooth ride. The stiffer sidewall absorbs less of the road imperfections than the tires filled to a lower tire pressure. Therefore this is felt throughout the suspension and hence driver and passenger cabin.

Also, higher pressures give better overall traction because the stiffer sidewall does not allow the tire to cavitate (roll under itself) hence allowing more tire to remain in contact with the road. The lower tire pressure allows for the sidewall to fold hence the "footprint" is reduced, hence less rubber, less traction.

Cheers

MadloR