I have a 2007 RX400h and I did install NEW tires with the size of 235/60/18. The tire pressure alarm is always ON and I can not get it off. ALL tires pressure are the same. What shall I do?

The most helpful authority for optional tire sizes with experience is probably "The Tire Rack"...online at "TireRack.com. These guys and gals are Pros at "Performance or Optional" tires. Remember after fitting your Corolla with any new tires...you need to include a four wheel alignment to insure the best performance, and mileage. Also be sure to confirm the recomended tire pressure.

Tire pressure is listed in a tag that is either in the driver's door jam or the driver side rear door jam. It's a sticker that also lists the tire sizes and other information for your vehicle.

Tire pressure is set by the manufacturer based on the wheel/tire size and overall weight of the vehicle. So always follow their recommended pressure, and not the max pressure stamped on the tires.

{: ) Check for excessive wear on any of the tires on the vehicle and then verify that all the tires are the same size, brand, and same model. It is also important to check and make sure the tire pressure is properly adjusted per the sticker on the door. The following examples listed below could cause this condition:
1. 2 tires on the vehicle are Goodyear P245/75R16 and the other 2 tires are Firestone P245/75R16
2. 2 Tires on the vehicle are brand new and the other two tires have excessive wear.
3. 2 Tires on the vehicle are Goodyear Wrangler SRA 265/70R17 and 2 tires are Goodyear Wrangler HP 265/70R17 (Same brand/different models)
4. Aftermarket Wheels and Tires (NON-OEM 20 inch wheels and tires)
5. Tire pressure is not properly adjusted.

Don't forget to check the full size spare tire pressure as well. I was pulling out my hair over this on my 06 rav, and then I suddenly remembered the spare. . .The colder weather had decreased the pressure in that tire to pop the alarm.

Hi,
If all the pressures are the same and you have pressed the reset button under the dash by your right knee location on the drivers side.
There could be a problem with the pressure feed back signal from the valve stem on each tire.
The dealer will have a device to pick up the pressures from each tire.
He will be able to confirm if the system is all functioning correctly.
Let me know if you need more information. Good luck!

Typically a tire pressure monitoring system uses an indirect measurement, and only measures the differences between the pressure in all of your tires. It does this by monitoring the speed at which the wheels are rotating. If one of the tires has low pressure, it will have to spin faster than the others, because the tire is partially flat, and the diameter of the tire is smaller.
If you are running different tire pressures in the front and back tires, then it might trigger the light to come on.
This might also be due to uneven tire wear or different size tires on the front and back.
Check the tire wear, and temporarily run equal tire pressure in the front and rear. It might take a few miles for the light to reset, so give it some time.

Are all tires at correct pressure? Some of the cars also use one in the spare tire. if the spare has a tire valve like the other 4 tires it has a sensor.

The proper tire pressure for the front and rear tires should be shown on a small sticker (placard) inside the driver door jam. Open the driver side door, and look for a sticker that shows the manufacturing date, and other information, such as the proper tire size, load capacity, tire pressure, etc.

The placard pressure is what you should ALWAYS set your tire pressure to, unless you have installed different tires/wheels than came with the car when new (and then it's anyone's guess).

The placard pressure is what the manufacturer has decided is the best pressure based on their testing for that specific vehicle. Whenever I have tire work done, I always asks the shop to inflate the tires to placard pressure. You'd be surprised, they often set the pressure wrong!

Hello partner. The difference in air pressure variations from a 16',17' or 20" tires is a non-factor. Any size tire will go up about 1psi per 10 degrees ambient temperature. The recommended pressure for an 03 Grand Cherokee is 33psi. So if it's a rainy 55 degrees in the great northwest when you set your pressures the temperature on your trip to Death Valley would have to climb to about 175 degrees. On a different note maybe your alarm just isn't calibrated correctly.

Yes you can set your tire pressure but make sure the tires are cold. After driving the car let it sit for at least two to three hrs. Then set your tire pressure to factory tire pressure.

You can find this setting in your drivers door jam. Their will be a sticker with a tire on it and it will give you front, rear, and spare tire pressure