Q: Our 2012 Lexus ES 350 has 35,000 miles on the odometer. At 25,000 miles, the dealership told me the tires needed to be replaced, but I declined. During the 30,000-mile service, done at a different dealership, the service adviser told me to replace the tires at the next service. To my eyes, the tires look fine, but ever since the weather turned cold, I have started getting a tire pressure warning. I checked the pressure on all the tires, including the spare tire, and they were all close to 32 pounds per square inch, the pressure recommended on the door sticker. The tire warning does not indicate any specific tire. I have not noticed any leak in the tires since I purchased the car. The car is due for its next service, during which I will ask them to reset the sensor warning. I would appreciate if you could advise me if it is OK to have the tires replaced at Costco, which will be a lot cheaper than the dealership. My only concern is that the tire pressure warning system function should not get affected, in case I decide to have the tires replaced at Costco.

A: I wonder if you are checking the tire pressure after driving a bit, at which point the pressure could have increased slightly. During a significantly cold morning start, the tire pressure could be below specification, which could be triggering the warning light. If you can’t check pressure and add air when the tires are stone cold, try setting them to 36 psi warm. You can certainly purchase tires anywhere. Just make sure the replacements meet Lexus’ standards for load capacity and size.

Q: I have a 2002 Acura RL with 100,000 miles. When the engine is hot and I come to a stop, I have no heat. Only cold air blows. Also, the temperature gauge never goes beyond the halfway point.

When I drive, the heat is great.

I have had three different gas stations try to determine the problem. The first station changed the thermostat. The second station told me I needed to change the thermostat and flush the antifreeze. The third station informed me after having the car for two days of testing that there was an air pocket in the system. After spending hundreds of dollars, I still have no heat when on idle.

A: It sounds like the system is not as full of coolant as it should be. Try checking the temperature of both heater hoses as the engine idles hot, with the heater on and the fan at medium speed. Feel both hoses at idle and then again as a helper revs the engine to 2500 rpm for one minute. If either or both hoses become noticeably hotter, you’re low on coolant. If one hose is noticeably hotter than the other (at any engine speed), you may have a malfunctioning heater control valve or cable connection, which isn’t allowing enough coolant flow though the heater core. A scan tool check of the air-mix door is also worth checking.