Those numbers are not "substantially" underinflated. Also tire pressures aren't checked every single time you bring it to the dealer. They are checked when they are undergoing maintanence services such as inspections or scheduled engine oil service, or if there is a specific complaint about wheels and tires.

Oh yeah? The X5's tire pressure monitoring system begs to differ with you. It was a substantial enough variance that it triggered the warning. It is great than 10%. The dealer should have had them adjusted correctly when it was new. This isn't a vehicle with 10s of thousands of miles here. Joel

Don't agree that the three tires were substantially underinflated. Marginally, yes.

Don't agree that the problem here was the monitoring system design or malfunction. It caught a 10% difference, so it did the job it was designed to do. I don't think it measured a low tire, it actually reported on a high pressure tire (relative to the others), if it was measuring the delta.

Agree completely that with a new car it would be nice if the tires were filled to spec. Blame the dealer who delivered the car, if it was within the past few months.

Proof positive that a tire pressure gauge is required equipment in a vehicle, monitoring system or not. What did we ever do back before computers were there to save us from ourselves?

A tire guage is required when you have computer monitoring of the tires??
Well what happens when the low oil light comes on?? Do you pull out your low oil guage??

Before I start, let me note that some vehicles actually have tire pressure monitors with senders. However, most don't. For these models.....

There isn't a computer monitoring the tires. There is a computer monitoring rotational wheel speed, and noticing a difference between any one wheel and the calculated average. Big difference. Given past problems with actual pressure senders on the wheels, I prefer this system. It doesn't replace a tire pressure gauge, it complements it. Those past problems include damage when tires are dismounted, balance, false alarms, and sensor failures.

Since we are designing for BMW here, let's take it one (small) step further: what is the point of on-board tire pressure monitoring with digital dashboard readout, if in fact there isn't an on-board tire inflation system? If you have to stop for low tire pressure, do you care which tire it is? Make it an automatic fill system. Why should anyone have to dirty their hands and fill up tires when the car could do it by itself. Heck, that way the car could correct for tire pressure at altitude, automatically. While we are at it, I want on-board mass-spectrometer oil analysis, with TBN and large-particle count included. That way my indicated oil change interval would be real, not hypothetical.

This is particularly aimed at the group that complains the car has too many electronic features that compromise reliability (I agree).

So, as I said in the prior post, let's thank BMW for leaving off additional sensors that can fail, and each get a tire pressure gauge. ;)

As long as the systems added are tested using real-world conditions, the "risks" and "problems" listed should be near nil. The option for this is used on many other vehicles successfully. "It's one more thing to break" sounds like what my grandfather once said about air conditioning.

Let me know how happy you are when you get the low tire pressure warning in a heavy rain storm, and you have to make a $600 decision.

Does one drive and risk that the tire cannot be repaired because it has been driven too long while flat? Or, is it just that one tire is under-inflated by three PSI?

The good news is that you'll have your trusty tire gauge in your vehicle, and you can get out and check the pressure. Keep dry.

Joel

Yep a good idea called common sense

If you want to do that then go ahead. But before you do ask your self "is this common sense?

The point some are trying to make is as long as vehicles are made by men we should have reasonable expectations regarding what we expect them to do in spite of what the brochure, salesman or other people tell us.

It's just common sense to have more that one avenue to accomplish a task. In this case it's called a tire guage. Personally i can see that it makes perfectly good sense. Some of us have spares in the trunk and guess what? we could use that device to check that tire if in fact we ever needed to put it on. :rofl: :rofl:

Different strokes for different folks, I guess. I feel that modern BMWs have too many sensors with too many nuisance failures. Maybe it is just me. I am with Barry, that it is just a common sense thing.

I have had one low pressure warning in the past 5 years, and I pulled in to a gas station to fill it up (I had my gauge with me). It was raining. I saved a $250 RF tire.

Others may prefer the on-board fill system (which I last saw on a first generation Hummer, IIRC). That system kept you completely dry. Of course, every pound that gets added to the vehicle reduces the handling and performance, so it is all a tradeoff. :thumbup:

JCL...for every pound added it effects handling.

I'll take the oil dipstick any day even if it effects the handling of my X.:rofl:

My dad will agree with you here. He's had two flats and has fought with VW twice (and lost) because the shop that fixed his flat damaged the sensors to the tune of a few hundred bucks a pop. Just something else to go wrong.