how often should i be putting air in my tires? my low tire lamp comes on a lot. the tires be at a little under 40 psi when i check them after the lamp comes on. i reinflate and sometimes in as little as two weeks or as long as two months the lamp comes back on.

 

I'm not sure what year/model your car is, so this may or may not be a factor, but have you checked your spare? I was at the Lexus dealership last week, getting my headlights adjusted and I asked the service writier if they were swamped with people rushing in to have snow tires installed. She said "No, we've had a TON of people coming in with low tire pressure warnings. As the temps drop, so do tire pressures. People check all 4 of their tires, and they appear to be okay. Most often, we find the issue is with the spare tire, which they forget to check." (I must admit, I would have never thought to do that myself).

I've also read in the manual that for the LS430, there is a re-set button under the dash, to establish what "normal" pressure in the tires should be. Have you used this button? (If not, that could be the issue, because Lexus only recommends about about 33 psi. If your sensors are being tripped just below 40 psi, the system is obviously "confused" about what normal pressure should be). Hope this helps...

 

Yes, I agree, 40 psi is too high for your car

 

You should check your tire pressure once a month. 17" LS430 recommended tire pressure is 32 psi. If your LS has 18" tires, the recommended pressure is 33 psi.

Buy a tire pressure gauge with a digital readout at your local auto parts store. Typically $10~$15...

If your LS is an 06 or earlier model and has a Tire Pressure Monitoring System (TPMS), it is an indirect system. What this means is the system compares the speed / revolutions of all four tires on the vehicle and can detect if one tire is rotating at a different speed than the others, based on it having less pressure than the other three. The tire pressure lamp will come on if this condition occurs. The pressure of your spare in the trunk is not monitored with this type of system.

On many other Lexus vehicles, including the LS460, the TPMS system is different. Each tire, including the spare, has a sensor built into the wheel that monitors the tire pressure directly and sends a signal to an on board computer. This type of system is called a direct monitoring system.

In my opinion, you're running too much pressure in your tires @ 40psi. I'd drop the pressure down to 32~33psi.

If you have chrome rims, some owners have experienced excessive tire pressure loss due to the chrome flaking off the rims around the area where the bead of the tire contacts the rim and makes a seal. If you don't have chrome rims, you shouldn't experience this issue. But losing 1 to 3 lbs of pressure a month isn't that unusual. Especially with seasonal temperature changes such as summer to fall or fall to winter.

Jim

 

ohhhhhhh!!!! thanks a lot. i was reading the psi that is printed on the tire itself. i have a 05 ls430 w/ 17s. i thought it said 40 psi. but i trust u guys and i will deflate to 32-33 psi. i guess the computer is confused if im putting too much air in the tires. once again thanks a million.

 

Do remember to reset the TPMS. If it was being tripped at 37 or 38 psi, it will almost certainly go off at 32 or 33. The reset button is hard to find under the dashboard...

 

i know where it is. i have been resetting it when i was inflating. thanks.

 

The factory recommended tire pressure for the LS430 is printed on a label attached to the right side of the door frame on the drivers door opening. Factory recommended cold tire pressure for 17s is 32 PSI. Pressure listed on a tire sidewall is usually maximum pressure for that tire.

 

That button there resets and reinitializes also the TPMS. It's two different things. Resetting is for when you have a low tire, and then you fill up and want to reset to turn the light off. If you go from one complete range or change to another (i.e. dropping from 40 to 32 psi, or get new rims, etc.) you need to reinitialized to tell the computer that "this now is the basis for monitoring when low."

So, if you're running 40 psi, then drop to 32 psi and just reset. The light will continue to come on after a few days, maybe even within a few minutes. You need to drop it to your new psi. Then press and hold that button for over 10 seconds and it will show "Initialized" on the dash display.

 

I had the same experience yesterday after rotating the tires. The spare in the trunk had not been rotated through the previous cycle, but after driving the car for about 20 miles, the low pressure light came on. After checking the pressure in the recently added spare, it was several pounds lower than the others. I added air and will then reset the TPMS. Is this button near where the volume **** for the exterior beep is located?

 

would try the nitrogen fill if anyone around ya has it available,, Costco filled with it when I had the Michelin's installed and they have not varied,, no leakage and very stable for expansion and contraction,,

Derry

 

I also have my tires filled with nitrogen at Costco. I am sure it helps but not sure how much. Pure Nitrogen certainly can't hurt since its a completely inert gas. Getting the remaining oxygen out of the inside of the tire is probably significant as it ages rubber.

I was surprised to relearn that normal air we breath is actually 78% Nitrogen content. So a pure Nitrogen fill only adds 22%.

 

Yes, we actually get relatively little oxygen from the dirty smoggy air we breath. That's why if you've ever taken to an oxygen tank and mask and given pure oxygen, your lungs and blood are replenished so much faster than when after running and we gasp for oxygen while breathing.

I would say pump it up with helium... lighten the car.

 

I thought the V rated 17" tire pressure recommendation is at 35Lbs.

 

I agree with nitrogen having a noticeable effect. I have my tires balanced at rotated at Costco every 5,000 miles and haven't had to add any air in between. Just did them at 25,000 miles on these Primacy yesterday.

Works for me.