Clean1

First of all, I checked the DIY section above and also the Search function, but did not see an answer to my question. I apologize if this has already been answered.

My dealer service adviser recommended inflating the tires to 36psi instead of the factory recommended 33psi. He said the slightly higher pressure would help prolong the tire wear. I followed his advice and my '08 LS 460 has 20,500 miles on the original 18" Bridgestone Turanza EL42's. They probably still have a few thousand miles left on them before hitting the wear bars.

However, with the arrival of the rainy season here in South Florida, I decided to purchase new tires because my wife is the primary driver of the LS. I do not want her to have any issues with tires slipping in the rain.

I purchased the Michelin Pilot Sport Plus All Seasons based on recommendations on this site and also because of the 45,000 mile wear warranty. The tire dealer inflated the new tires to 44psi. When I questioned him on the elevated tire pressure, he said it was well below the maximum tire pressure of 51psi. He said that that is the pressure he recommends even though Lexus recommends 33psi. On the ride home from the tire shop, my wife complained that she could feel every tiny bump in the road. I checked the pressure and the pressure in hot tires was up to 49-50psi. I lowered the pressure to 40psi hot. I will check the tire pressures again tomorrow morning, after the car spends tonight in my garage.

I am planning to run the new tires at 36psi cold, the same as I did with the Bridgestones unless the opinion here is for a different pressure.

Any advice will be appreciated.

Johnny

The 33psi cold will rise anywhere from 36 to 39 hot under operating conditions, especially in warm climates like yours. Similarly, inflating the tires to 44 psi cold could indeed raise it to the tire's limit and, while the corner wear may be reduced, the tire's load will be concentrated in a smaller zone, i.e. the center of the tread. This will overheat the tire in this area, accelerating wear, reducing traction (especially when cornering), and contribute to a much rougher ride. Your tire installer really doesn't know what he's talking about, and I will put my faith in the tire and car manufacturer over an installer any day. In fact, his off-the-cuff opinion is downright dangerous...

rominl

iTrader: (4)

44psi that's pretty dump..... that will likely get premature wear on the middle section of tire... the tire installer is stupid

i can see how 36psi is a good number, the brakes on the ls460 should be able to handle it

and btw, all pressures are measured at cold as a reference

miniz

Of course the dealer wants to over-inflate your tires. You will wear the centers down to the cords faster and thus need to buy new tires from him quicker. Run your inflation as the factory specs posted on the drivers side door shut. Under or over that number by a significant margin will cause excessive tire wear that will void Michelin's warranty. The car will also ride like a go-cart, as every possible vibration will transmit into the cabin. Bring them down to 33psi.

Craig B

I run 35 psi cold in all four of my tires...

jlawr

If you do city driving ONLY, 33psi is fine. It'll feel very comfy.
If you drive in the city AND on the highway 36psi is preferable.
36psi will also increase treadwear without sacrificing comfort or performance.

Remember 36psi will need to be checked when tire is cold - winter or summer.

Johnny

One more thing I forgot to mention. When you adjust your tire pressure, make sure you reset your TPMS. There's a simple procedure in your Owner's Manual. If you don't do this, the display will read out inaccurate numbers. Resetting creates a benchmark that the ECU uses to compare to the actual pressures in the tires.

Clean1

Thanks for the all the replies - I set them all at 35psi cold this morning.

Johnny: I was not aware of resetting the TPMS procedure. Thanks, I did that as well.

jmcraney

My understanding of the TPMS is a little different than yours. As I understand it, the accuracy is inherent in each tire sensor and that all of the sensors are independent. I believe that the display just displays the information that is supplied by the sensors. As for the "Benchmark" my understanding is that benchmarking is the process of informing the car's electronics as to the correct cold inflation pressure or normal pressure which is captured from the sensor inputs when the reset button is pressed. I believe that the low pressure warning threshold is calculated at 20% below the benchmark and is on a per tire basis. Benchmarking or reseting at any pressure other than the accurately inflated cold pressure will compromise the ability of the TPMS to warn you of dangerous conditions or cause the TPMS to false alarm. You should only need to benchmark or reset one time unless you decide to use a different cold inflation pressure or the the TPMS performance is anomalous. Of course if you don't know if the TPMS has been benchmarked correctly then you should do that. And I don't believe that the stored benchmark information is lost if the car's battery is depleted or disconnected.

wsteiner

This is my understanding too. Your not resetting the tire pressure sensors, you are resetting the warning system. You reset only when a sensor has been replaced, or you want to change the alarm setting.

rominl

iTrader: (4)

that's my understanding too (jmcraney). resetting the tpms is just to set a new "reference" as to when to trigger the tpms warning light, but the pressure itself it will detect fine without resetting?

AceVA

Lexus told me that this has less to do with tire wear (personally, I find OEM tires to be garbage anyway) and more to do with the fact that when cold weather sits, people were bringing their LS's in because the tpms light was on. They recommended raising the pressure to compensate.

The ride difference is very noticeable to me when it's at 38. I keep mine at 33-34.

Johnny

I ran around for a year getting readings on the display that did not agree with the actual pressures at the individual sensors, until I reset the system. After this I checked the tires randomly and the readings there matched the ones displayed on the monitor. So anytime I adjusted the cold pressures after that, I also reset the system.

Thanks for the input guys!

jmcraney

I understand that it can be confusing. I wrestled with mine for a while before I got it clear in my mind. You have to accept that if the sensors agree with each other but do not agree with your air gauge then there is probably a problem with the accuracy of your gauge. All of my sensors are right on when I check mine with a high resolution/accurate gauge and I think as a rule the sensors are very accurate. If you have one sensor that doesn't agree with the others then I would suspect the sensor accuracy.

Here is a link to a tire gauge that has both the accuracy and resolution that you need to benchmark your tires.

http://www.amazon.com/Moroso-89560-T...291892&sr=1-13

Strad6708

Hey guys,

Sorry in advance, but I am probably the least mechanically inclined person you'll encounter on here. My two week old '10 LS460 AWD indicates the tire pressure to be anywhere between 38 to 41, depending on whether the tires are cold or not. Should I adjust this down to 35 or 36 since I do a combination of driving on bumpy city (Chicago) roads and the interstate and want a balance between really soft ride and long treadlife? To make this adjustment, do I literally let air out of the tires until the TMPS indicates the pressure numbers I want? Which of the 5 numbers is the spare? I guess I'll figure it out by seeing which numbers change.

P.S. - jmcraney, since I saw you posting on this thread, just a quick comment that at 80 mph I have not experienced any unusual wind noise. There were some strong cross winds yesterday that were causing a little wind turbulence, but today the winds were calm and there was no noise. Pheew. Crossing my fingers!

Allen