CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2017 Lexus LS 460 - Pressure

This is a comment about tire pressure referencing “Pump up those Tires.”
I take both my Lexus LS460 sedans to the Lexus dealer for all servicing. Although the manual cites 33 psi for the tires, the dealership always fills them to 36 psi. I learned the reason is that tire pressure gauges do not record the correct pressure because I live in Albuquerque, New Mexico, which is over 1 mile high. I investigated on the internet and learned that we need to compensate for the altitude when measuring tire pressure.

I always read your column in the Drive magazine supplement in our newspaper. My cars are relatively trouble-free and never get mentioned. This is the reason that I like the Lexus line. (We had Camrys before.)

Bill Fienning

No, you don’t. The tire gauge is referenced to atmosphere, it is only a differential between atmospheric pressure and the pressure inside the tire. 5000 feet up, the atmospheric pressure is lower so the absolute pressure IN the tire is less because of this but the differential is still 33 or 36, whatever the gauge reads. The pressure in the tire is there to support the weight on the tire and that only changes a tiny, tiny bit with altitude.

And besides, this is tire pressure, not rocket science, 3 psi will make such a little difference in any measure of tire performance, it won’t matter. Won’t matter, except to fed the OCD of folks on the internet.

Your dealer puts 36 psi in 1) Because all tires lose pressure over time and the dealer figures most drivers will never check it on their own so they set it a bit higher. OR 2) Your pressure gauge or their pressure gauges are not accurate - I vote both. Or it could be both 1) and 2).

4 Likes

No need to correct it. If you fill your tires at that altitude and then you drive to a (significantly) higher or lower location the pressure in the tires will change. And the temperature will also change the pressure inside.