Junglequac

While I was getting an oil change and rotation yesterday, I had the dealer lower the PSI to 35 from 40 and the difference in ride quality is honestly striking. While I know mileage well might be affected due to running lower pressure and perhaps tire wear my be negatively affected, but I must say from the short duration since I got the car back, the juice seems well worth the squeeze.

So my question to my fellow 4th gen owners is what PSI are you folks running?

tofu

mine @ 38 PSI..

SW17LS

It makes an astounding difference. I run mine at 31. Lexus recommends 33.

DarKnight

iTrader: (3)

I keep mine at 35.

roadfrog

33 psi as per the door jamb recommendations from Lexus.

213374U

In the 32-34 range

aw001

31 on the handheld electronic measuring device and 34 on the car display console...

Junglequac

I will revise downwards. Since I purchased it, it was at between 39-40 PSI and compared to my 2005 LS430 UL, the ride quality was terrible. The difference after changing it to 35 was not subtle. It finally rides like a luxury car!

It had been bothering me for a while, but the tires were both brand new (previous owner) and filled with Nitrogen and I was somewhat reticent doing myself due to the aforementioned Nitrogen,

While I have always been aware at just how much of a difference tire inflation makes, I just cannot get over just how much better the car now rides, Later today, I am going to take it down to 33.
My sincerest thanks to al who have replied.
Best,
JQ

jmcraney

I keep my tires inflated such that the tire-pressure display in the dash shows 33 PSI for all five tires when I first start my car in the morning. The 33 PSI was determined by the OEM tire manufacturer and the car's manufacturer. The tire pressures vary about 1 PSI for every 10 degrees of ambient temperature change - decreasing when temperature goes down and increasing when temperature goes up. The pressures typically go up as you drive your car due to warming caused by tire flexure during rotation. Air has to be added to the tires periodically to compensate for permeation losses and a seasonal pressure adjustment is required depending on where you live. I benchmark my TPMS for 33 PSI on all five tires so as to provide a 25% low-pressure warning threshold of 25 PSI - if the pressure in any tire falls below 25 PSI the warning appears in the dash display. If you are adjusting your "normal" pressure down from 40 PSI to 33 PSI you should benchmark the tires at 33 PSI to avoid nuisance low pressure alarms because they probably have been benchmarked at 40 PSI (warning thresholds 30 PSI). Nitrogen provides a negligible advantage and is not worth the cost or hassle.

sktn77a

iTrader: (2)

Fresh air is 80% nitrogen:20% oxygen. Oxygen has a higher atomic number and molecular dimension than nitrogen so diffuses more slowly through the tire. Tires wear out long, long, before oxygen does any damage to the rubber compound.

So who came up with pure nitrogen to inflate tires? (Oh, yes, the sales department! $$$$$$$ )

R Z

Speaking of tire inflation, I've had this slow leaker for a while. Lexus sees nothing wrong, but every few months or so the low light indicator comes on. I generally run out somewhere for a buck and pump it up. This past weekend, the light came on again. It showed the same tire at 27psi. I think 28 will turn off the dash light. So, I pulled out my bike pump and pumped the tire up to 33. So far, so good. And I got a good work out,

Nospinzone

My guess is there is nothing wrong with your tire, but with the seal with the wheel. The next time you get new tires, make sure they scour the edge of the wheel where the tire seats. Over time crud can build up there and make for an imperfect seal.

As to tire pressures, I set mine at 35. I've always gone a couple higher psi than the manufacturer recommendation, except on one car.

Many, many years ago I read that the car manufacturer and the tire manufacturer are always at odds about the recommended psi. The car manufacturer wants the pressure lower so the car rides smoother, and the tire manufacturer wants the pressure higher so they can claim the tire lasts longer. I have no idea if any of that is true, but I've always believed it. I think I read it from an article by Tom McCahill in his column Mail for McCahill in Mechanix Illustrated.

roadfrog

Nitrogen is also stable at all altitudes. Doesn't change. I don't use it in my cars, but if I drove in various altitude changes, I might. It's the reason that it's used as propellant in Pepper Spray......so that it will always dispense at the same velocity and range at all times. Geeky I know...but true. lol

Junglequac

I am witcha about Nitrogen, It just so happens that is what the PO used when he replaced the tires about a month before I purchased the car. They now have around 5000 miles on them. They are the OEM Michelins.

mckellyb

I run 40 PSI in mine, but may revise that downward when I put Conti DWS06s on in a few weeks.