[Please help]

Hello all. I am new to BMWs and to run flat tyres. I have recently purchased a new 3 series.

I have a F30 with 225/50/R17 94W tyres all around.

I think I am being a bit dim, but pillar b seems to imply that I should be inflating the front tyres to 2.4 bar which I think is 34 PSI and rear tyres to 2.9 bar which is 42 PSI.

Not sure if I have interpreted this correctly and was wondering if this is correct and why the rear tyre pressure is higher than the front ones ?.

Thanks in advance.

[HighlandPete]

Originally Posted by Please help

Hello all. I am new to BMWs and to run flat tyres. I have recently purchased a new 3 series.

I have a F30 with 225/50/R17 94W tyres all around.

I think I am being a bit dim, but pillar b seems to imply that I should be inflating the front tyres to 2.4 bar which I think is 34 PSI and rear tyres to 2.9 bar which is 42 PSI.

Not sure if I have interpreted this correctly and was wondering if this is correct and why the rear tyre pressure is higher than the front ones ?.

Thanks in advance.

The door shut placard will give two settings, for a given tyre size. We'll typically be somewhere in between the two pressure extremes, according to our driving conditions, monitoring tyre wear, and loads we carry.


Yes, rear tyres are a higher pressure, RWD being one factor, BMW's established pressures for best handling balance another, and you'll notice we increase the rear tyre pressure more than front when running the higher settings for more load.

HighlandPete

[BeachsideF30]

32 on staggered m sport 18's

[Dog Face Pony Soldier]

I believe the rear tire pressure listed on the pillar assumes maximum cargo load is present. I suggest you lower the rear tire pressure slightly when less than maximum passengers and cargo are on board.

[carzaddict]

35's on square m-sport rims

[Please help]

Thanks all for taking the time to reply. I did think the tyre pressure for the rear set looked a bit on the high side.

I currently have 34 PSI at the front and 38 PSI at the rear.

[S4NoMore]

33 psi front 35 psi rear, cold, on my square 225-18 Contis. With iDrive coded to show actual pressure I'm seeing about +2 psi all around for typical steady-state driving.

[Please help]

Thanks. I didn't realise you could code the idrive to show actual pressure. Is that that easy to do ?

[S4NoMore]

Originally Posted by Please help

Thanks. I didn't realise you could code the idrive to show actual pressure. Is that that easy to do ?

It requires getting set up with an OBDII/serial cable and E-Sys, which is about a 5-6/10 difficulty, maybe a tad higher or lower depending on your fluency with a computer. Check out the DIY/Coding subforum for more details.

[Please help]

Originally Posted by S4NoMore

It requires getting set up with an OBDII/serial cable and E-Sys, which is about a 5-6/10 difficulty, maybe a tad higher or lower depending on your fluency with a computer. Check out the DIY/Coding subforum for more details.

Excellent. Many thanks for that. I will have a look to see what I can find on the subject.

[junkyjunky]

Originally Posted by Please help

Excellent. Many thanks for that. I will have a look to see what I can find on the subject.

You also need the TPMS sensors in the wheels. In Canada, it is built into the ABS (not sure if this true all the time). I coded this on my car, not realizing that was the case, so all I get is blanks for tire (tyre) pressure and temperature, but a green indicator implying all is well.

[Please help]

Originally Posted by junkyjunky

You also need the TPMS sensors in the wheels. In Canada, it is built into the ABS (not sure if this true all the time). I coded this on my car, not realizing that was the case, so all I get is blanks for tire (tyre) pressure and temperature, but a green indicator implying all is well.

I currently get the green indicators too but it would be great if it showed the actual tyre pressure in each tyre. I have had a very quick look at the link which shows the coding. Looks a bit too complicated for me !!!.

I assume the dealership would charge a premium to have it done ?.

Thanks

[junkyjunky]

Originally Posted by Please help

I currently get the green indicators too but it would be great if it showed the actual tyre pressure in each tyre. I have had a very quick look at the link which shows the coding. Looks a bit too complicated for me !!!.

I assume the dealership would charge a premium to have it done ?.

Thanks

Haven't checked to see what the dealer would charge, but I would guess so and then there's the variable of if they would even know how to do it.

I'm pretty familiar with computers, so the coding was not that complicated. However, Shawn in the DIY coding forum is of tremendous help and there is a plethora of how-to's and guides in there too. The added benefit is that there are so many other things you can open up in your vehicle that you would have had to pay big $$ to get.

[Please help]

Originally Posted by junkyjunky

Haven't checked to see what the dealer would charge, but I would guess so and then there's the variable of if they would even know how to do it.

I'm pretty familiar with computers, so the coding was not that complicated. However, Shawn in the DIY coding forum is of tremendous help and there is a plethora of how-to's and guides in there too. The added benefit is that there are so many other things you can open up in your vehicle that you would have had to pay big $$ to get.

Thanks again. I think I will have to have a proper read when I have a bit more time.

[S4NoMore]

Originally Posted by junkyjunky

You also need the TPMS sensors in the wheels. In Canada, it is built into the ABS (not sure if this true all the time).

Hmm I didn't know that this was possible in the F30. I wonder if it can be coded for US cars. I was looking at winter tires for a friend with an Audi on tirerack, and noticed that TPMS sensors are not required because Audis use wheel speed to calculate differences in rotation and detect any issue. This saves a significant chunk of cash.

Originally Posted by Please help

I assume the dealership would charge a premium to have it done ?.

It's worth a shot to ask, maybe your dealer is friendly and kind enough to offer, perhaps for a half hour of labor.

[Please help]

Thanks. I think I might just give them a call at some point. Would certainly be a very useful addition to the green indicators that are already on show.

[botis1028]

I use 2 lbs heavier than the door says. Most of my miles are highway and don't have any potholes where I live. This helps keep the mileage up a little.

[G30 B58]

You: Drives: 2014 335i M-Performance AW/CR

Originally Posted by botis1028

I use 2 lbs heavier than the door says. Most of my miles are highway and don't have any potholes where I live. This helps keep the mileage up a little.

...and your concern is keeping your gas mileage up.

[botis1028]

Originally Posted by F32 N55

You: Drives: 2014 335i M-Performance AW/CR





...and your concern is keeping your gas mileage up.

Not really concerned about mileage, I get about 27mpg. I've just always kept a little firmer pressure in my tires - for long trips you can see a slight gain in MPG if you go a little firmer.