general problems of the 2002 Infiniti Q45

Right rear tire suddenly began to lose pressure, as much as 5 psi in one mile of freeway driving. I kept stopping to air up tire, confirming low pressure with accurate bourdon tube-type gauge. After four stops to air up, problem quit. When I reached destination city, set up service appt. With local Infiniti dealer. After four days of a long weekend, including slow-speed and freeway driving of over 200 miles, pressure loss had quit. Cancelled dealer appointment. Three months later, problem occurred again. Had tire checked at ntb, no leaks found. Tire dismounted, checked on inside, no defects or punctures or blisters found, wheel in good shape, tire remounted. One month later, problem occurred again, this time losing 10 psi in two miles of freeway driving. Aired up. Lost 5 psi. Changed to spare. Dealer mounted new tire. Pressure dropped two days later. Dealer installed new wheel (couldn't exactly match existing color--great on a $60k car. ) and remote pressure sensor. Problem cured. Cost: new tire--$350, tossed tire with 30k left on it (suspected of being cause)--$350, new take-off wheel--$800, new sensor--$260. Total cost, including mechanic and trashed good tire--$2,000. No diagnosis ever offered.

I had a problem with my car, with the tires constantly leaking. I had to fill them with air all the time, had them checked a number of times, and had to have the rims cleaned and reground, etc. , trying to determine and solve the problem. After incredible aggravation, we finally tracked the problem down to cracks in the valve stems. The valve stems contained the air pressure sensors and were expensive to replace, parts were as much as $135 or so each, plus labor, which could be $200 or more, and then all the tire pressure sensors had to be re-set - I think the term was recalibrated or something, which most places didn't have equipment to do or couldn't do correctly, and I always ended up having to go to a dealership. At least they sometimes didn't charge as much as they could, as I was a captive; if they didn't do it, none of the sensors would work. I discovered that these valve stem sensors were subject to cracking, and had just been put on the car for that model year. Midway through the model year, they were replaced with another type made out of better material. Before my model year, the type used was in service I think for several years. The mid-year replacements were used for the next several model years. This all suggests that they knew there was a problem, but avoided paying for it or issuing a recall. Could you please investigate? thank you.