Greetings All,

Why would the Dealer set tire pressures to 38 psi max when the door says 30 psi?

Thanks,

 

Did you measure it cold or hot? If you measured it after driving, you're doing it wrong.

 

Tire pressure light came on, wife had it checked at the local station and discovered a screw in the left rear tire. It was slow, was topped of and repaired the nest day. The screw was close to an inch from the edge. It was repaired by a plug. The pressure light came on after that and she took it to Lexus and he told her that they inflate to 38 psi because when the tire heats up it will go up a bit.

So the question is why will the dealer on new tires put in 38 PSI when the car door says 30 PSI?

 

Because it depends entirely on the tire installed and what they feel is better. The 30 PSI is a general guideline set by Lexus based on their testing and shouldn't be regarded as what you should set the pressure for, no matter what. Why is that? Because it can also depend on tire wear. If 30PSI is too low for the tire, the edges will wear more than the tires. The proper pressure is dictated by a combination of noise level(typically more noise with higher pressure), tire wear, and gas mileage.
The dealership may be doing it because they want to improve gas mileage, because it was something that the manufacturer to told them, or just a random number set by some random person. If you can get even tire wear, the noise level is fine, then running 38 PSI is fine(as long as it doesn't exceed the maximum pressure when hot).

And measure your tire pressure cold.

 

Thanks. I was just frustrating dealing with the tire pressure sensor as it made my wife nervous. Hard to put air in tires that are cold as you have to drive to the gas station...but I'll check them all when they are cold to see if they are even including the spare.

 

38 PSI is high , sometimes they can make a mistake at the repair shop. 38 psi for sure will give you a very rough ride on the ES350 , I also have an ES 350 and i usually keep mines at 34 or 35 psi. Any higher and i can tell the difference as the ride is very rough . look on the tire itself, it may have the recommended psi for the tire. Get a good tire pressure gauge and I suggest u take some air out of it.

 

Mfg. recommends 30 psi for all around normal driving . This is the optimum tire pressure for a comfortable , smooth quiet ride. Normal tire rotation will provide you with the best wear for that brand tire. If some want to play with various pressures it's OK as they need to be the judge of how they want the car to ride. I am about to replace my OEM Bridgestones after 35,000 miles as they are almost down to the wear bars. The ride even today is quiet and smooth and I have always kept the tire pressures at 30 psi. Do what you like and enjoy the ride.