Check you Tire Pressures!
 

I had been wondering if my ride was overly harsh because of the runflats, but haven't check my tire pressure since picking up the car from the dealership. (~2500 miles so far) I checked them today, and they were at 50 psi!!!! TPM senses change of relative pressure, not absolute. It can't tell what the exact pressures are, just whether it's + or - relative to the last time the TPM was reset.

Yes, you would have thought by now I would have checked the tire pressures. But nevertheless, I adjusted them back down to 35 psi and things are sooooooo much better.

Same for me too. When I took delivery of my car 4 months ago, I thought the ride was really rough, and too "sporty". The PSI was between 50-52. I adjusted them also, back to 35psi, which is what is called for with the 20inch Y-spoke wheels. I wonder why both our dealers would make the PSI to dangerously & uncomfortably high?

I just had my 20" y-spoke wheels put back on yesterday and the ride feels really harsh too.

Mine weren't much higher. Supposed to be 32psi front and 35psi rear for staggered 20" Y-spokes.

I guess the ride is going to be harsher than my winter wheel/tire combo...

Same here... They were ~ 42psi... However, since this is the 3rd car that was delivered to me with the overinflated tires, I knew what to do on the day 1 :)

Mine were at 40-45psi after I had my 214s put on by a tire/rim shop. I asked them why and they said it gives 25% more cushioning (protection) against bumps for the rims. 35psi is of course acceptable and softer. I think I'll stay with 40psi as a compromise.

40-50psi is normal for run-flat and low profile tires. I'd set them to 42 in the front and 45 in the rear. I've found the wider your tires are, the better the ride is. 30-35 psi only relates to non-low profile regular tires on rims 17" and smaller. If ride quality and noise is a problem, I would suggest you buy a set of non-runflat tires. Runflats have thicker and reinforced sidewalls so you sacrafice ride quality and longevity, for safety.

Have to disagree with these and some of the other recommendations posted above.

My E70 X5 came with 214's with summer run flats. The sticker on the door says:
275/40 R 20 XL Front 32 PSI
315/35 R 20 XL Rear 35 PSI

This matches what's on page 236 of the Owner's Manual for X5's with 3rd row + Sport Package too.

Why would one want to inflate them more than what BMW recommends?

:iagree:

I agree with the recommended pressures on the door. For you guys and gals that don't check your tires after about 10 K miles and see if the center part of your tire is wearing faster than the edges. that's what usually happens if they are overinflated.

The new tire control system does not work any more with pressure valves. It's now the ABS control which checks the wheel diameter and detects if the diameter changes, meaning you have a pressure lost.

^ well what's really "overinflated" if the tires say 44psi max? Would 40psi be overinflated? Also, the sticker figures aren't considering non-runflats, correct?

I know my sticker specifies figures for 19s only so they are pretty individualized. Yours may be for summer sport runflats only. Looking at the manual, it's recommending 32/32 for 275/40/20 and 315/35/20 if you have 2 rows of seats. That's pretty damn low on my non-runflats cause when I had them all at 35 it was already pretty low. The guys who put these specific tires on rims all day told me 40.

Always kind of amazing to me that stlrs delivering a $70G car, and
a "performance/luxo" brand at that, can't come up with a better
pre-delivery insp gig/guy than the 8 buck an hr car washer with a bad
air gauge.

like I said in a previous post...when you get about 10,000 miles on them see how they are wearing. If your centers are wearing more than the edges then you have been overinflated. That way you can tell if your tire people are right. if they are not right you will have to replace your tires quicker. If they are right you can ride around all day with a big grin :rofl:

I believe it varies by country. In the U.S. manufacturers are going to Direct Pressure monitors to comply with Safety Regulations.

http://www.xoutpost.com/tire-wheel-br...-info-fyi.html

In the US the e70 does not use ABS to calculate tire pressure. There are TPM in each wheel, which is the reason there are plastic caps on the valves, metal ones may cause interference with the signal.

All newer BMWs use TPM in the wheels, here it is:

It's #7 in the diagram.
http://www.realoem.com/bmw/showparts...27&hg=36&fg=15

Interesting. So will the ABS Value Stem Caps sold by BMW parts (accessory item) cause interference? Anyone know what they are made out of (I hope ABS isn't an acronym for the material it's made of).

Weird,
My '02 Vette has TPMs, each wheel, (Vette has had the system for several years), and it
has metal valve stems and metal caps. Never a prob., even when re-tiring to non-RFT tars...
GL,mD

I use metal caps on my Lexus and it doesn't cause interference. They also say not to use metal caps. They say they can cause corrosion. I also think the dealers over inflate tires during the PDI so the tires don't get flat spotted...

Craig

i would suspect that higher inflation pressures = better fuel economy. this maybe the reason why they did this at the factory. The 4.8is isn't terriby fuel efficient in the first place so lowering the tyre pressures may make it worse.

the average consumer won't know to check the tyre pressures after delivery.

The factory overinflates the low profile tires to prevent flat spots from developing while stored and shipping. The dealer is supposed to correct the tire pressure to the recommended PSI before delivery, but unfortunatly, they rarely get this right.

i checked my tyre pressures this morning and they were 32psi all around. I left them this way.

Penguin,
Thank you for the precision. More details about this here:

http://www.xoutpost.com/tire-wheel-br...tpm-light.html