My '08 RX 350 has the low tire pressure warning none of the tires are low! It has done this before and promptly goes off after a low tire is aired up. What's up?

 

Checked the 5th (spare) lately?

There are 2 types of systems ,,, one with senders in each tire (including spare) and the other checks the rotation difference.

Salim

 

What is rotation difference?

 

flatter (lower pressure tire) will have less circumference and will spin more to match up with the more air in the other.

Think of two horses pulling a carriage. The horse with shorter strides has to take more steps to keep up.

Can some one confirm RX350 uses which system?

Salim

 

i thought it was individual tire sesnors but I hadn't heard of the 2nd option you describe. rotation seems like the more sophisticated system of the 2. +1 on being interested on which it is.

 

Very seldom will you find a clear winner, in making design choices ..
The rotation based delta has the flaw that when both the tires deflate equally (and it must allow a margin for turning).

Salim

 

The rotation system is not a more sophisticated system. In fact, it did not work too well, thats why Lexus went to the direct system.

 

Pumping that spare is a pain. Doesn't feel very luxurious...

 

Thats why I always pump my spare 5 psi higher.

 

Do not underestimate the discomfort, when the spare has no/low-air and is needed.

Salim

 

i have a 08 RX350 as well and this morning when i was heading to work i noticed the tire pressure warnning too...

this actually happened last year as well around this time. So i went my dealership and they said that it has something to do with the climate ( like if the weather is cold i guess it will expand?).

Could someone confirm that ?

 

Other way
P --proportional-> T

So if all other things remain the same with lower temperature the Pressure will fall.

The recommended pressure is with tires not driven (cold). As you drive the sidewalls get squeezed and the temperature builds up, which increases the pressure.

With the onset of winters, the undriven tire temperature further falls.

Salim

 

ahhhh yess haha
my brains not functioning well without coffee =P

so would you suggest i bring it into the dealership?

 

Bring it into the dealer to pump up the tire pressure???? Only Lexus owners would even think of doing something like that

 

lol ^

Actually i checked my tires and they were all @ 35 psi which i believe is normal so it must be my spare and you need to bring that to the dealership to do correct me if im wrong...