Today the low tire pressure warning came on. So I took my tire pressure gauge and found the driver side rear about 5 pounds below the others (about 28). Of course it would be SO MUCH EASIER if the car displayed the pressures directly (like the LS460L I drove last weekend). Anyway, I had someone else drive the car and I examined the entire surface of the tire. Did not find any nails. Went to the local auto parts store trying to get some nitrogen to refill the tire. Apparently they dont sell such a thing. So just topping off our nitrogen filled tires requires a trip to the dealer ??? Sounds absurd to me. I have my 5,000 service in 2 days so I will have the dealer address it then. I wonder how much they will charge for that !!!

Bottom line, has anyone found a place to purchase a can of nitrogen so that the owner can refill the tires ??? Seems like someone should make a can with a valve and a fitting to put on the valve stem. Not a hard concept. If they sell freon for the owner to use you would think they would sell nitrogen too.

The gas mileage has gone down about 1 mpg also. Is the car that sensitive to the tire pressure ???

Thanks in advance.

 

IMHO, the Nitrogen issue is over-rated. If I were you, I would've just topped off the low tire with normal air, it's not worth risking driving around on a tire that is significantly lower in pressure than the others - google Ford Explorer/Firestone for proof . . .

 

not sure about the cost but you can also try costco, i believe they also fill with nitrogen

 

Nitrogen is no miracle, just put some reg air into it. For whatever reason it lost 5 psi, it will happen again. Check for nails and such or the valve on the valve stem.

 

In the old days you were supposed to periodically check your tire pressue and adjust it to match the number on the door sticker. I guess today we are just supposed to drive until the warning system tells us it is low and then take the car to the dealer???

 

Or you can buy your own tank of nitrogen. lol

Just fill it with regular air, you will be fine and won't even notice a difference.

 

Funny you mentioned that. Same thing as my car. My passenger rear was 25psi, the rest were ~30psi. Btw, does Lexus have a low pressure sensor in the spare? I ask this cuz when Costco checked my spare tire, it was at 30psi, but it was supposed to be at 60.

And GOD knows what was running in Lexus's mind for putting the tire rest button in such an awfull place. Granted you don't need it that often but still even my Sienna had it in a place where I could reach it.

 

Update -

Took the car to the dealer today for the 5000 mile service. The one tire was down to 26 PSI. They checked and said all 4 tires were low. They could not find a reason and topped them off. It would not be a big deal if I could just do it myself. I guess I will have to ask them to top off the tire pressure the next time I take it in for a wash and see if they do it for free.

Asked the service writer - the spare has no pressure sensor.

Is there a reset button that needs to be pressed to reset the low pressure reading? Where is it located? Thanks.

 

Its in the book.
But...instant gratification always wins. Follow your steering collumn. Just when the plastic runs out, theres a bump. Thats the button they want you to press to reset the tire sensor while putting your car into ac-on. And either I did it wrong, or thats where the user manual is messed up. Mine doesn't tell me that the reset worked except for the flashing tire sensor. At least the sienna was just on the side where our button box is. AND one of the other Lexus cars I was loaned has it in the LCD display. You cycled till you got to the tire pressure warning reset. They should've done that for our car.

Oh and the Costco guy set up mine to 36psi since I brought the car in hot. He said it would settle to 33psi. Either my tire pressure stick is wrong, or even at cold I still read 36psi. I hope that aint too high.

 

Thanks for the update. I did look it up in the book. Just for clarification - I know the button is used so the TPMS can learn the current tire pressure. It then puts up the alert if they drop a certain amount. Does one need to use the button again if you just add air to a low tire to bring it back into spec? Seems like the warning should go away by itself since the tire is now within spec. Thanks.

 

if you have a full size spare...then you got a sensor. so all together you got 5. we always set press. at 35 psi.

also there is a 2nd switch...dont remember exctaly where its at but check passanger side under dash or open the glove box and around the edge.

also if the tire light is flashing, then you have a problem other than a low tire...ex. the sensor is low on batt., in this case you have to replace the whole sensor...which means money. lol.

 

boxcarfan -

Thanks for the info. I had asked the Lexus service advisor the other day if the full size spare had a sensor also and he said no !!! I also asked him if the sensor transmitted a pressure to the car and the car verified the pressure or if the sensor just transmitted a good pressure / low pressure indication. He said the sensor just transmits a good pressure / low pressure indication. That seems to not be the case also if one must initialize the car to know the base pressure reading.

According to the manual the second swithc is under the glove box near the center console. It is for those who swap out wheels during the winter months and have 2 sets of sensors.

 

that service ad. is dumb imo. when i hook up the techstream and go under TPMS i can see the tire press of all 5 tires down to the tenth of a psi. and i can see at what press. the TPMS light will turn on. its either 5 or 7 psi under what you set it at will turn the light on.

and another reason the light will flash is if you accidentally hit the 2nd switch...we get SO many cars in with that problem lol.

so at all times, the computer knows the exact press of each tire, and knows the exact press at which it will turn the light on.

 

I wish they let US know what tire needs air.

 

Also, any Lexus that has a full size spare will have a TPMS in it.

IMO, nitrogen is more trouble than its worth. Too little benefit for all that trouble.