highmiles

There has been a lot written about the ride quality on the 06 GS. I even posted some information on my 11 hour drive on Monday and questioned the tires or the suspension setup.

This morning I had the bright idea of checking my Tire Pressure. I know... I know I should have done this long before putting 1000 miles on my GS but I guess I assumed that since I had the tire pressure sensor that it would take care of it for me. It wouldn't shocked me given all the other incredible things I find every day on this car. DUMMY ME.

I FOUND 40-42 PSI ON EACH OF MY TIRES!!! (18" Yokohama Run Flats)

I adjusted them to the recommended 33 PSI and WOW what difference. I should have know better because I always check my tires after my routine Lexus services on the 98 GS but somehow thought that the tire pressure sensor did more that what it is really designed to do which is to check for LOW PRESSURE not over inflation. I guess I forgot that the 06 GS is still a car.

06 GS430
Flint
Ash
Loaded
18" 5 Spoke Graphite

Sandman

I'm glad you brought that up. I mentioned in another thread that I found my Yokohama's to be inflated a bit high (35-36psi instead of 33). Your situation was much worse at 40+psi. That could even be dangerous. At 33 psi I feel that my GS handles more optimally and I get rattled around less too.

You might want to call the service manager to report this. That is quite an error that is unsafe and with the number of miles you drive just cost you some money with decreased tire life. At least you wore down the center of the tread whereas most tires tend to lose the outer tread first due to under inflation and hard cornering.

I understand the the tires don't have an individual pressure sensor in each wheel like some cars. Instead the car measures the rotations of each wheel and when a tire gets low in pressure the radius decreases and therefore it starts to have more rotations per mile, compared to the other wheels. At a certain point the controller flags the problem. I don't know if the manual states a pressure limit that it can detect. But this would be good to know. Does it tell you when you are down to 25psi or does it have to wait until you are at 10psi?!?

Just curious, are you sure that your gauge is accurate? I have 2 gauges - 1 analog and 1 digital and they both read within a half a psi. But I did have one that read way off at one time. Also, you probably know that temperature changes affect pressure too. Not sure what the weather has been like in OK lately. In Atlanta at this time of year we can see 30-40 degrees change over a few days. If your tires were inflated on a very cold day and the weather has shifted up 20-25 degrees you could see an extra 4-6psi. Vice versa if the temp drops.

CK6Speed

iTrader: (1)

I'm sure others tha work or had once worked at dealerships can confirim, but the car is usually shipped with very high tire pressure to prevent and flat spotting while being shipped and while sitting on the dealer lots. Once the car gets its PDI, the tech supposed to adjust the tire pressure to its proper setting. More often than not the tires get missed. Technically, it means the tech did not properly do a PDI on the car.

chuckb

I was in the shop area when they were setting up a new GS430. When the tech checked the tires, they were at 72PSI!!!!!!!!!

spwolf

btw, toyota in Europe has 2 reccomended pressure settings - 32psi for normal driving, and 15% more for over 100mph driving... I wonder if it is the same with Lexus, and they might usually tell dealers to set it at 40 psi for safety reasons, and then dealers blindly doing it w/o thinking.

Rockville

The SC430 will take up to 45 lbs. if you are driving at 150 MPH a lot SPWolf over on the Autobahn. This is one of my pet peeves and it must be a conspiracy of Techs to overinflate or underbleed during the PDI. At first I would think that their Air Pressure gauge was different than mine so I tried a new gauge and got the same reading. I usually check them one last time before delivery because it will seem jittery and harsh at 40 lbs on any of the Lexus. BTW Sandman on the GS300 we use the tire pressure sensor at the valve stem not the wheel speed inference type we use on the LS430 and RX330. It is a similar setup to the SC430. We also use this type on the GX470 and the spare tire also is included in the pressure reading. It will let you have the pressures as high as you want but will warn you if they drop 7 lbs to 11 lbs. I don't think that 40 lbs. would wear your tires out in a short time like a month and it would have some traction benefits in a competition application. I used to run 60 lbs. on my Mini Cooper for autocross runs. The ride quality will suffer and the snow traction would be worse. If anyone has new tires put on make sure the shop is familiar with the pressure monitors because they are very expensive to replace. The last page of your owner's manual will give the factory tire pressures and they vary by model and rim size. The LX470 has a different setting front to rear. And then there is personal preference.......

highmiles

Thanks Sandman for the info. I have a high dollar tire gauge that I bought from Griot's Garage (I love that place) that I use religiously on my 98GS. I really can't fault the dealer who I have said great things about on CL. I showed up at 5:30 to drop off my 98GS to prep for the local dealer's GS Event and was then told that my new 06 GS430 had just been unloaded from the truck. The guys in service stayed late to PDI my car so I could take it home that night. By 7:00 I was sitting in my new GS so I can understand that they might overlook tire pressure.

Neo

iTrader: (3)

It's not that bad. I ran 38psi when I had 18s. Yes it rode slightly stiffer than at 33psi but with less rubber on the sidewall, a little more air protection is warranted. I am at 40psi now with my 20s. I am also not the only one who follows this practice.

If these were 16s, then 4x would be a bit high but on low profile tires, it is not uncommon to be at a higher pressure.

Sandman

After reading your post I checked the manual - and I see now that the car does have sensors in each wheel. Thanks for the information and correction. Didn't mean to mis-inform. I have been reading so much lately that I can't remember where I read it but I almost swear that I saw some "official" info that said that the tire pressure system on the GS was the less sophisticated rotation rate sensor. I remember being disappoined that each wheel didn't have a sensor. Anway, I stand corrected and I'm very glad to know that each wheel has a pressure sensor.

I also saw in the manual that there is one (or maybe 2) system initialization/reset button(s) located down by the drivers knee airbag cover. I looked with a flashlight and I didn't see a button. Maybe it is under the panel. Any idea if this is concealed - or know how to find it?

My 225/50VR17 Yokohama's have a Max rating of 40psi. I think that this is a fairly common number to see the mfg recommend as max. Specs usually have margin in them but the question is how much. From what you say and what others have said sounds like it is fairly common to disregard the Max inflation rating. I understand that increasing pressure increases performance to a point by stiffening the sidwall performance and getting the center of the tire tread into the action. But 60psi? Wow. Is that safe?

Sandman

My 01GS had a "flatspot" issue. I remember that they seemed to work themselves out with a little driving. Very interesting what you say - I didn't think of that but it makes sense that the pressure would be raised during transport to minimize this effect.

Sandman

Neo, how did you find your tire wear to be with the higher pressure? For everyday driving does it make a big difference in performance?

We can probably expect 15k-20k miles from the stock tires on the GS. I wouldn't want to do anything that is going to make me have to replace them any faster. Unless it makes a big difference.....

I'd love to hear what you think the pros and cons are.

Neo

iTrader: (3)

I don't think it made a big difference but it was noticeable. It's not like I took every move hard though. It was mainly for the extra protection. Maybe it's in my head but I felt better knowing I had a little more air in there.

Now, I had Michelin Pilot Sports on the 18s and the max pressure was I think 51psi. 38psi is nowhere near the max. On the Nitto 555s now, I think the max is high too (too lazy to run out to the car ) so 40psi is not near max either. With the setup, I had no uneven wear issues and got about 25k miles on them. The rear was pretty worn but the fronts had probably at least another 5k to go.

rheiy

When I run my summer setup on 18's, I keep the psi at 41 all the way around. A lower psi at 32 or 33 will cause the tires to wear quicker