Tire air pressure question

[X5 Meister]

I noticed that the new X5 (E70) has 2 sets of recommended tire inflation pressures. For driving under 100mph and driving over 100 mph. I've never seen or heard of such a thing. Does this have something to do with the new run-flat tires that are spec'd on it?

[Wagner]

Hmm, read the sidewall of the tire and see what it says.

[X5 Meister]

Sidewall? I'm referring to what BMW has written in the manual.

[Wagner]

I know that, I'm referring to what the tire itself says. If you seem to be confused by the manual, read the actual tire for what it says the spec should be. You said you wondered if it was because they were run flats, well read the tire itself.

[X5 Meister]

I never seen a tire that tells you what the proper inflation pressure should be, especially given a particular load. The spec is usually in the manual or on a door jam sticker. My point was that BMW now is listing a spec for different speeds, which must be a new thing.

[Wagner]

You've never seen a tire that tells inflation pressure?

[motordavid]

My guess is the new TP rec'd is a euro reg and/or liability deal:
could be RFT related or, more simply that most very high
continual speed, requires TP to up to snuff, eg higher than
normal, as opposed to underinflated, which will quickly induce
sidewall flex, tread flex, more heat and kaboom, potentially.

Meanwhile, back at the ranch, there are few niches in the
US of A, where one can run a car at 100+ for any length of
time...thus, it's Autobahn CYA, imo.

MrGruber, ya'll taking this stuff you read a tad too much to
heart, imo. Common sense prevails and it doesn't mean a
wit, imo.

Higher loads, as in your X is packed for a trip: more air.
Normal driving around: 32 or, whatever the damn sticker
says.
Keep 'em pumped to what you like.
GL,mD

[JCL]

Originally Posted by WagnerX5

You've never seen a tire that tells inflation pressure?

That isn't the proper inflation pressure, as was asked, that is the design limit for inflation, relating to the design limit for maximum load. It is not vehicle specific.

[JCL]

Originally Posted by mgruber

I noticed that the new X5 (E70) has 2 sets of recommended tire inflation pressures. For driving under 100mph and driving over 100 mph. I've never seen or heard of such a thing. Does this have something to do with the new run-flat tires that are spec'd on it?

It is not specific to run-flats. I have seen lots of vehicles with different pressure recommendations based on expected driving speeds, long before the advent of run flats. I suspect that the practice has just arrived in the US now, via a Euro tire inflation recommendation label.

[X5 Meister]

To WagnerX5 : I hope you are joking about the inflation pressure on the tire itself. If you are running your tires at that pressure then all I can say is I hope never to get run over by you since you probably have zero traction at all times. Personally I've never heard of a single case where a car manufacturer recommended running tires at there max cold inflation pressure, as printed on the sidewall.

To JCL : Thanks for the info. It answered my question perfectly.

To MotorDavid: Don't worry, I'm not taking it to heart. I just found it interesting that BMW NA would put something like that in the manual. I've owned a number of BMW's in the past and I've never seen them do something like this, certainly not in the USA. Anyhow, I just wanted to share it with people, that's all. The info might be useful to someone, who knows.