Almost every new car I bought had overinflated tires. My theory is that they are purposely overinflated at manufacture for tire seating and then should be set to the proper inflation at delivery time, which is overlooked. I think too that lawyers got involved as it would be less liability than under inflated tires.

 

Funny, most cars I recall tires being a little under inflated. As far as safety goes, each tire is marked wit ha maximum cold pressure, which on the 18" summer tires on my NX says 51psi. If set to 51 cold, the pressure may climb to 55-58 on the highway on a hot day and the tire is still safe. In fact the higher the pressure, the less heat the tire generates. If your driving in very hot conditions on rough roads or with a heavy load, higher tire pressure will keep tire temps down and thats safer for the tires. Also the maximum rated pressure still leaves a big margin for error.

 

I picked up my Ultrasonic F Sport today and I asked about the tire pressure when the tech was showing me around the vehicle. They were properly set at 32 psi. I asked about the over inflation typically seen and he said that they are delivered over inflated and they replace air with nitrogen at the proper inflation as soon as they get on the lot. This is done at Lexus of Royal Oak in Calgary.

 

I'm dealing with this exact problem. Delivery the tire pressure was at 38psi, but the door sticker has 32psi. I reduced to 33(been steady 33x3 and 34x1 for some reason lol) and there hasn't been any issues/notifications until today when I the sensor was giving me a warning because the pressure was at 34/35 mixed. It was the chilliest morning we have had so far. I just emailed the sale rep and he said they set it to what is on the tires (36 or 38). Should I just reset the tire pressure sensors and leave it at 33?

 

I would leave it at 33 PSI. If you go with the max pressure indicated on the tire sidewall, you will have a very rough ride. You probably won't be loading the Lexus with enough weight to get the tires up to their max weight.

 

Not necessarily true, especially if one fills their tires with nitrogen, as my dealer did for me.

 

With the door sticker marked 33 psi and the tire marked 51psi, you have a safe range to work with. 33psi I would consider a minimum and the car should ride smoother at these lower pressures. As the tire pressure climbs, the handling should become sharper and the ride may become slightly harsher.

Also, the sidewall is marked 51psi cold, which means that tire pressure will climb higher at high speeds and in hot conditions, and this is fine. The 51 PSI max cold pressure allows for higher pressures. Many cars, especially european cars are often marked "36PSI cold *39psi for 100+ mph travel"

 

I have mine set at 35psi and they rise to about 37-38psi when driving.

I keep them a little above the minimum to help with gas mileage and I find the ride isn't noticeably rough.

 

Hi
sorry but i didn't get you, how does the higher tire pressure setting allow for more increase?
isn't the over way around? during summer you should lower the tire pressures so to allow space for increase when it becomes hot?

 

Higher tire pressures help keep overall tire temps lower. The heat in a tire comes from the rubber flexing as you drive. Think of a paper clip that you bend back and forth over and over. The metal gets hotter until the clip brakes in two. A tire works the same way. Under inflated tires flex more as they roll and pressed to the ground. This flexing increases heat. So as road temps increase and speed increased so does tire temps.

 

Tread depth plays a huge role also UTQG ratings ....and tire profiles. It's not just air pressure. I like to find the best pressure that suits me.
Usually 2-3 psi higher but not always.

 

I have 30 on all 4. When it drives, the psi changes to 31 or 32. Is it bad?

 

I'm one who believes that if you follow manufacture's instructions (on the door), you will not go wrong. After all, why would they want to mislead you? Some may want a softer ride with lower PSI, but in the end probably will result in excessive wear of tires.

 

What about the Ford/Firestone fiasco? Ford was specifying 32 PSI and had lots of blow outs, big problems. The same tire was use on Chevy Trailblazers but Chevy used 36 PSI and had no issues.

Fortunatly tires are built to take abuse far beyond their rated limits.

 

30 PSI may be rather low. It's safer to be over inflated, even 50-60 PSI will be safe but result is a harsh ride and center tread wear, but the tire wont over heat or fail. While 20-25 PSI may be dangerous to use on a fully loaded vehicle in hot conditions or on the highway.