I know, another tire pressure thread... I'm very sorry about this but I have read through about 30 - 40 threads and still didn't get a solid answer, so I thought I would ask again.

Just brought the car home this weekend and the tire pressure light went off again. Now the car went through a Pre-Purchase Inspection at the dealership and passed with flying colors. It is also still under factory warranty so I'm not terribly worried at this point.

First things first - parked the car and checked all the tires. They all read between 29 - 30 PSI. So I figure that is most likely the root of the tire pressure warning. Simple solution, add some more air and reset the TPMS. I've also check the valve stems and they are all tight.

Here's the question: 2007 MCS with 17" Pirelli Run Flats (205/45R17 from memory). The manual says (under 100 MPH) 36 PSI but the sticker on the car says (under 100 mph) 38 PSI. I figured I looked at something incorrectly so I grabbed the manual and sat down next to the open door and looked again. That's exactly what it said.

So which is it? 36 PSI or 38 PSI? I hate to generically split the difference, I would like to know what the actual correct pressure is.

Thanks,
Corey

 

door. 38

My Contis say the same, though I leave them at 32-33 lol... theyre almost toast anyway.

 

I use the 38 and don't have any issues.

 

i run my MINI at 40psi. I run them higher because of increased fuel efficiency, but you have to sacrifice some comfort.

 

Thanks Guys! Going to set them at 38 PSI this evening then.

I was leaning towards following the door sticker as I figured it would be more car specific than the owner's manual.

Guess if they are too harsh I can drop down to 36 PSI in a few weeks.

 

Just remember one thing as the weather gets colder the pressure will change.

Set mine last wednesday at 38 with a temp of 78 degrees in the afternoon when i got gas. Used my own pressure gauge so i know i have the right pressure.

Saturday morning the temps were down in the low forties and I had a warning light light. Checked the pressure and it was down at about 32-33 and this is normal for that kind of temp difference.

Temps are supposed to stay low for a week or so. So i added air to bring them up to 38.

 

Mine are up near 40. They are too stiff to notice a few pounds difference anyway

 

Cool - thanks Chris. Off to air those little puppies up right now

 

I believe the proper pressure for RFTs is about 1000 PSI. This, combined with a meat grinder and a stamping machine, will turn them into a proper composition for something useful, like a doormat.

 

Hahaha - lol

Hey MCSfanboy - I'm a Kansas City boy myself. Grew up in Overland Park & Leawood for many years. Graduated from Blue Valley North in 1990 but now live in California near Oakland and San Francisco. Just wanted to say "Hi" to a fellow Kansan

 

I wondered about your screen name. I figured you must have some connection back this way. I went to Shawnee Mission North ('80), but my sons go to East. Let me know if you're ever back this way and I'll get a bank loan and buy you something at Starbucks.

There's only four reasons I can think of why you went to California:
1. Because you heard the college chicks were hot, but you couldn't pronounce their names and they dumped you.
2. Because your girlfriend (boyfriend?) moved there
3. Because you can buy medicinal cannabis
4. Because it's the one place where it's "cool" to live in your car

Just having some fun mate! I've been there many times and love the place. My cousins use to live in Oakland, but like all proper bay citizens, they retired in Oregon.

 

If you checked the pressure and then set it when youhad been driving for a while, then yes, that would be normal.

You should always check the pressure cold. At teh track you could gain 7-8-9-10 psi due to temp changes and tire construction.

 

Well, tire pressure is at 38 and so far no complaints from the girlfriend about changes in ride quality and no TPMS warnings - so far so good

 

Well done! Great list - at least made me laugh. I will tell you that although I'm not allowed to anymore, being a straight single guy out on a Friday or Saturday night in San Francisco is like shooting fish in a barrel most times - even for an ugly mug like me And if you like traffic, crowds, and paying too much for most everything around you, California is the place for you... Been here 6 years and really like it but honestly can not wait to move back to the midwest in the near future.

 

17in tires take 38psi & 41 for speeds>100mph. The risk with low profile tires is that as outside temperatures drop in the fall the tire pressure drops rapidly. It will kick on the Low Tire warning and you'll have to reset it.

We just went from 80F to 35F in IN and my wife's Taurus tires dropped from 32 to 26psi while my Cooper Run-Flats dropped from 38 to 22. Can't explain the reason other then the Run Flats have less volume and so the temp drop is more dramatic.
So remember to check & adjust the pressures the day after your temps first drop in the fall and anytime it's dropping more then 20F.
Your Low Tire warning will tell you also.
Sunny skies & drive like the wind.

 

17in tires take 38psi & 41 for speeds>100mph. The risk with low profile tires is that as outside temperatures drop in the fall the tire pressure drops rapidly. It will kick on the Low Tire warning and you'll have to rest it.

We went from 80F to 35F in IN and my wife's Taurus tires dropped from 32 to 26psi while my Cooper Run-Flats dropped from 38 to 22. Can't explain the reason other then the Run Flats have less volume and so the temp drop is more dramatic.
So remember to check & adjust the pressures the day after your temps first drop in the fall and anytime it's dropping more then 20F.
Your Low Tire warning will tell you also.
Sunny skies & drive like the wind.