droppping tire pressure - The Unofficial BMW M5 Messageboard (m5board.com)

M'nd · 30th October 2002, 19:02

Anybody notice that the tire pressure is always falling. I will set my pressure and a week later it is low by 4-6 psi. Is this due to driving habits or something else. Just curious if anyone else notices their pressure always off from what they recently set.

MEnthusiast · 30th October 2002, 19:05

are you checking before you do any driving on the tires? same time of day? same location (in garage, outside) etc? if all else is equal- how about the falling temps of the past few days- that coud be the cause.

M'nd · 30th October 2002, 19:12

cold tire pressure only. I won't change pressure unless she has sat all night. This happens in summer and now in the fall.????

greg · 30th October 2002, 22:13

Def. not normal to lose that much - but this seems to differ by brand. My dunlops lost more naturally than my Kumhos do. Still, I would assume anything more than 1 lb a week (and that would be a lot) is a sign of something else wrong. Are you seeing this in ALL the tires? If so I would suspect measurement error - using the same gauge? What is the temp at measurement time? Expect roughly 1 PSI change for each 10 degrees (fahrenheit). (Hey - how come fahrenheit is a German word but Germany uses Celsius??)

If in one tire it is a screw (most likely), a bad valve (unlikely but possible) or even a bad rim. We had a Honda once. Some jackass at a tire place used an impact wrench to reinstall the wheels and WAY overtorqued the bolts. He almost certainly did it all in one step as well, without roating around, every other bolt, working up to full torque in 2 or 3 stages as you should. End result was a cracked rim and a very slow, very hard to find leak. We replaced the wheel and all was well.

M'nd · 31st October 2002, 18:06

the drop is equal in all the tires. I'll buy another gauge and see if it is the problem. I have been using this gauge for several years and on lots of different cars with no problem like this.
thanx