Recommended tire pressure OEM 35/41

[mojo1]

My M Sport tire pressure at "b" pillar states 35/41 PSI. When I took delivery the pressures were set at 28/33. The ride was compliant at the lower pressures but gave some tire squeal at semi hard cornering. I bumped the pressures to manufacturer recommendations but the ride changed drastically to the worse. Currently I have the set at 32/35 seems about right to me. What have you set your tire pressure at.

[annoyingmouse]

With most cars I've owned, I've had to try a few different pressures to find what feels right. When I drove a Mazda MX5, I ran my tires slightly softer than recommended, and with the Volvo, I ran the front tires harder (37psi) than the rear (33) despite the sticker suggesting 34 all around.

My base X1 (17" non staggered wheels) recommends 32 front and 38 rear, and I haven't found any set up that's noticeably better so far.

[RPM90]

Originally Posted by mojo1

My M Sport tire pressure at "b" pillar states 35/41 PSI. When I took delivery the pressures were set at 28/33. The ride was compliant at the lower pressures but gave some tire squeal at semi hard cornering. I bumped the pressures to manufacturer recommendations but the ride changed drastically to the worse. Currently I have the set at 32/35 seems about right to me. What have you set your tire pressure at.

I don't know exactly, but take a look at the B pillar specs again and take notice of the standard tire pressure psi, and the "high speed" psi.

There will be a difference of a few pounds between the 2.
If you tend to drive at higher sustained speed, such as a lot of highway driving, or carry heavier loads like a lot of people, then the higher pressure is recommended.

If 35/41 is the standard psi, then I would NOT go lower than that.
The reason is that the tire pressure has been determined to work with the X1's weight and suspension to give you best handling and ride.
If you go under that pressure your handling will not be as good as it is designed to be, because your tires sidewalls won't have the pressure needed to maintain proper sidewall stiffness that is calibrated to work with the suspension tuning.

Also, with under inflation you run a greater risk of damaging the tire and the wheel. The tire can be damaged due to increased sidewall flexing that will increase the tires temperature at speed. The sidewall can become much hotter than intended and that will weaken the tire compound. Couple that with the additional flexing and it can lead to sidewall structure fatigue and potential failure with a sidewall failure.
With RFT's the car will keep you safer as it can maintain adequate structure to let you safely stop or get to a repair center.
Still, not a good thing to allow to happen.

The other negatives are quicker and excessive tread edge wear as the tires contact patch is distorted, along with greater tread wear in general.
Your MPG can also drop as the tires shape is flatter causing more friction than is intended or needed.
This might seem like a good idea as one may think there is more tread contact with the road for increased traction. But the opposite happens due to the other factors at play like the softer sidewall and greater flex that allows the tire to "roll" on itself increasing wear and heat in the sidewall.
That's why you're hearing more tire "squeal" as there isn't really more usable tread contact as low sidewall stiffness is allowing the tire to lose it's functional shape and it can't maintain proper traction. You're hearing the tire squirming and squealing cause it's in distress, and it's telling you to feed it more air.

RFT's by design have a very firm sidewall structure and don't as much "give" as non RFT's to soften the impacts from road imperfections.
That's what causes the more jarring impacts that get transferred through the tire, through the suspension mounts and steering components and then through the body structure and steering wheel, to you.

I would put the pressures where they need to be for the safest handling, and best tire wear, and best MPG.
Running under inflated will simply wear the tires out faster, and RFT's are not low cost.

If you really can't stand the ride, then try a set of non RFT's.
That's what I did with my 135i and current '13 335i Msport.
Within 3 months from new I had tire rack install a set of ultra high performance all season Conti DWS tires.
Fantastic tire on both cars, resulting in a much nicer ride especially when hitting bumps or road imperfections.
Handling, traction, and braking still great compared to the stock max performance summer only tire, Bridgestone S001 RFT.
Both cars had the higher "highway" tire pressures.
Great wear, great MPG.
335i with staggered set up, I get between 27-28 MPG, calculated by hand in the traditional way.

Sorry to be so long winded.
I have a tendency to do that.

[HBWT]

Originally Posted by RPM90

I don't know exactly, but take a look at the B pillar specs again and take notice of the standard tire pressure psi, and the "high speed" psi.

BMW stopped having "high speed" pressure recommendations many years ago. The Ford Exploder/Firestone fiasco had everything to do with that. All manufacturers with which I'm familiar post only the "high speed/fully loaded" pressure. To the best of my memory, BMW's most recent "high speed" pressure was only for the rear tires. Because of this, it's my belief that lowering the rears 3-4 lbs is perfectly safe and I've been doing it for years without incident. But it's up to the individual to make their own choice.
BTW, with Winter coming and temps dropping in the coming days/weeks, you can count on MOST cars on the road having LOW pressure in their tires. It's time to check your tires, people!

[Bill B.]

Originally Posted by HBWT

BMW stopped having "high speed" pressure recommendations many years ago.

No, BMW still does. Check the owners manual pages 228-233.

[HBWT]

Originally Posted by Bill B.

No, BMW still does. Check the owners manual pages 228-233.

edit...stopped printing it on the placard on the door jamb.

[Lucky13]

I just looked at my X1 and yes it has a yellow high speed sticker which I never noticed before. The recommended standard pressure is 35/38 with my summer performance Goodyears but the high speed number is 38/42. I'll never drive over 100 so it really doesn't matter. Had my E93 335 up to 142 so maybe I need to check it.

[0w40X1]

Originally Posted by mojo1

My M Sport tire pressure at "b" pillar states 35/41 PSI. When I took delivery the pressures were set at 28/33. The ride was compliant at the lower pressures but gave some tire squeal at semi hard cornering. I bumped the pressures to manufacturer recommendations but the ride changed drastically to the worse. Currently I have the set at 32/35 seems about right to me. What have you set your tire pressure at.

That 35/41 was the same as my 2002 Dodge Dakota PU which never felt right.

I finally settled on 40 psi cold or 44 psi hot all around either fully loaded or unloaded.

So I took my X1 s28i to HPR raceway and tried different pressures using a laser temp gun to even the temp across tire.

I also measured the temps while driving at 75 on a hot day.

I settled on 38 cold (80 deg f ambient) or 42 hot (driven at 75 mph) on all 4 tires.

I have the summer performance Pirelli P7's, and they are very good except they seem bouncy at any pressure.

In a few years I'll have a light weight tire like Continental DW.

[CIWS]

Also remember the pressure affects gas mileage.

[Rotherd31]

I typically follow the msnufs advise.