[izzyM2]

I did not see a particular post regarding this topic. I posted on the winter tire pressure thread but did not exactly get the answer I was asking for. I’m in SoCal so winter temps are not significantly too low but in general shouldn’t I be following what the App is recommending for daily as I would think it is base on the exact tire we have versus what the forum says or on the door jam. I was running what the app was saying new from the dealership and I thought going down to 33 psi (cold) would feel better (not that it was bad) but I thought it felt a bit sloppy and felt more movement on the chassis.

[Bearded-Driver]

when i got mine the PSI on the tires were set to like 45 and 47 front and rear while the recommended pressure was saying 32.1 fronts and 33.6 in the rear which was weird. the next day I lowered the pressure in the tires down to 35 front and 37 in the rear. now with almost 500 miles on the car it says front and rear recommended is is 33 front and rear lol. as I drive the car it changes a little which is weird.

current pressures are reading in the car at 33 front and 36 rear on their own and seem to be staying. Its winter here and the weather has been going from cold at night to about 50 in the day and not much flux has happened.

maybe try running the reset function in the iDrive system settings for tires

[Carefree]

Originally Posted by Bearded-Driver

when i got mine the PSI on the tires were set to like 45 and 47 front and rear while the recommended pressure was saying 32.1 fronts and 33.6 in the rear which was weird. the next day I lowered the pressure in the tires down to 35 front and 37 in the rear. now with almost 500 miles on the car it says front and rear recommended is is 33 front and rear lol. as I drive the car it changes a little which is weird.

current pressures are reading in the car at 33 front and 36 rear on their own and seem to be staying. Its winter here and the weather has been going from cold at night to about 50 in the day and not much flux has happened.

maybe try running the reset function in the iDrive system settings for tires

It’s not weird. If you have any physics and/or chemistry in your background you’ll remember that pressure, volume, and temperature (pvt) affect each other. It’s called Boyle’s Law.

[JABCAT]

Follow the door jamb sticker & you'll be fine.

[M3SQRD]

Originally Posted by JABCAT

Follow the door jamb sticker & you'll be fine.

…or the < 100 mph and > 100 mph tire pressures in the manual

[izzyM2]

Originally Posted by M3SQRD

…or the < 100 mph and > 100 mph tire pressures in the manual

I did not look at the manual but I did see that it was setup at >100 mph on the tire setting in the car itself so changing that updated the app to read the tire pressure recommended on the door jam. Thanks!

But why would BMW recommend higher TP for higher speeds when I thought lower would be ideal for increase in grip.

[JABCAT]

Originally Posted by M3SQRD

…or the < 100 mph and > 100 mph tire pressures in the manual

Correct. Assuming OP isn't driving >100 mph on public roadways, the door jamb sticker is the correct cold pressures. And it really should read sustained speeds >100 mph (e.g., track), but I'm sure the general recommendation relieves BMW of any liabilty.

[JABCAT]

Originally Posted by izzyM2

But why would BMW recommend higher TP for higher speeds when I thought lower would be ideal for increase in grip.

From Tire Rack

"Because of the weight they bear, pneumatic tires' sidewalls bulge and their treads flatten as they roll into contact with the road. This results in dimensional difference between the tire's "unloaded" radius (i.e., between the center of the axle and the top of the tire) and its "loaded" radius (between the center of the axle and the road). The engineers call the difference between the two radii "deflection." Increasing vehicle speed will cause the tires to deflect quicker, and increasing vehicle load will cause the tires to deflect farther (if tire pressure isn't increased).

Consider that a 225/45R17 91W Standard Load tire (with a 25-inch overall diameter) will roll about 835 times every mile. Although the number of tire revolutions per mile doesn't change significantly as speed climbs, the revolutions per second become daunting. While the 225/45R17 91W-sized tire rolls a rather comfortable 7 times per second at 30 mph, this same tire will roll about 16 times per second at 70 mph on an American Interstate and an amazing 35 times per second during a 150 mph cruise on the German Autobahn. Thirty-five tire revolutions per second means that the tire is transforming from its unloaded to loaded shape and back every 3/100th of a second.

The European Tyre and Rim Technical Organization (ETRTO) establishes the standards for tires sold in Europe, and recognizes that the tire's deflection must be minimized and controlled in order to surpass high speed driving stresses. In order to accomplish this, the tire inflation pressure recommendations and the tire's rated load capacities are customized when speeds exceed 160 km/h (99 mph) for all tires up to and including a V-speed rating, and when speeds exceed 190 km/h (118 mph) for all tires that are Z-speed rated and above."

[M3SQRD]

Originally Posted by JABCAT

Correct. Assuming OP isn't driving >100 mph on public roadways, the door jamb sticker is the correct cold pressures. And it really should read sustained speeds >100 mph (e.g., track), but I'm sure the general recommendation relieves BMW of any liabilty.

Good point. Should have stated lightly vs heavily loaded tire pressures

[M3SQRD]

Originally Posted by izzyM2

I did not look at the manual but I did see that it was setup at >100 mph on the tire setting in the car itself so changing that updated the app to read the tire pressure recommended on the door jam. Thanks!

But why would BMW recommend higher TP for higher speeds when I thought lower would be ideal for increase in grip.

Higher pressures at higher speeds question answer above. The other reason for higher pressures is if your car is heavily loaded with luggage and/or people which the TR article addressed.

[kyrix1st]

What tires do you have? Tire pressure may not be the source of your problem, as winter tires in general tend to feel loose due to its highly soft compound (softer = less crack-prone in low temp.)

[izzyM2]

Originally Posted by kyrix1st

What tires do you have? Tire pressure may not be the source of your problem, as winter tires in general tend to feel loose due to its highly soft compound (softer = less crack-prone in low temp.)

The Miches

[1stM]

I'm using 36F and 40R (-2psi)

[JABCAT]

Originally Posted by 1stM

I'm using 36F and 40R (-2psi)

Those pressures are for speeds >100 mph/160 km/h.

[1stM]

Originally Posted by JABCAT

Those pressures are for speeds >100 mph/160 km/h.

Yes, I occasionally go over 100 mph (in Mexico)

[Ravenseal]

32 psi front and rear. Go to Costco and get Nitrogen fill.