Ah, wow. When the light came on I had one tire at 33psi and the rest were 35-38 so I just assumed the 33 one was low, rather than the 38 being high. Thanks for pointing out the door placard--I didnt realize it was there and it recommends 32psi. I lowered them quickly by hand so I've got the rears at 34 and the fronts at 33 right now, and I'll finish tweaking them down to 32 tomorrow. Tire pressure light is still on though, so hopefully it'll reset by morning.
So I drove about 3 miles this morning already and the light is still on. After driving a little bit and the tires heating up, three are reading 34psi and one is reading 35psi. It's so weird because I took a long road trip a few weekends ago (about 1,000 miles) and I inflated the tires to between 38 and 40 psi for the trip and the warning light never came on. That's why I assumed a tire must have been underinflated rather than overinflated. I don't know why that would change and suddenly it's warning me about overinflation.
Anyways, I've got about an hour commute to work in a little bit, so hopefully I'll see the light turn off during the trip.
---------- Post added at 07:09 AM ---------- Previous post was at 07:03 AM ----------
So I just checked the owner's manual and it says this:
"As an added safety feature, your vehicle has been equipped with a tire pressure monitoring system (TPMS) that illuminates a low tire pressure telltale when one
or more of your tires is significantly under-inflated.
Accordingly, when the low tire pressure telltale illuminates, you should stop and check your tires as soon as possible, and inflate them to the proper pressure. Driving on a significantly under-inflated tire causes the tire to overheat and can lead to tire failure. Under-inflation also reduces fuel efficiency and tire tread life, and may affect the vehicle’s handling and
stopping ability."
It doesn't seem to mention that the light could turn on due to OVERinflation, only underinflation. I'm really starting to think that there's just a problem with the TPMS.