[C.J]

On my way to work today, I had the 'Low Tyre pressure' warning flash up on the iDrive.

I immediately took it to the local tyre company to check it.

I have 255/30/19 & 225/35/19 RFT (with the ZCP style wheels from CM Wheels). They checked all 4, which were showing 45-60 psi

Now, they've reset all 4 to 32/34 psi, and I've reset the iDrive. Since leaving I felt the steering was heavier, and felt like it was tram-lining very easy.

Any advice? Why were they set extremely high?

I've just took a photo of each tyre:

Rear OS

Front OS

Front NS

Rear NS

[seanblee]

The old pressures were too high, but it sounds like the new ones are too low. Something around 36psi front / 38psi rear should feel rather better.

[C.J]

I've only owned the car 3/4 weeks, so I can't understand why they were so high to begin with?

[seanblee]

Because someone set them too high? 45psi could be about right for fully laden pressure, but 60psi is insane - the only time the tyres should see pressures like that is to seat them in the bead when they're being fitted.

[C.J]

I assume going from 60 to 32 will be the reason my steering feels heavier now? (bearing in mind I've only driven the car on 60psi, which felt light).

What would you recommend? 38 front, 40 rear?

[seanblee]

I'd start with 36 front, 38 rear then adjust slightly if necessary.

[AlwynMike]

Look for the correct pressure on the plate next to the drivers door.
On my Touring, for your size tyres, it should be 39psi (2.7bar) front and 46psi (3.2bar) rear for normal usage - yours may be slightly different.

After running at 60psi (not only dangerous, but illegal as well!!), I would expect the steering to be heavier as you effectively have more tyre on the road as it isn't "ballooning".

Mike

[djgandy]

I'd start with whatever it says in the door. Probably something like 2.7 bar (39) rear, 2.5 bar (36) front.

You are unlikely to have a TPM, you have Flat Tyre Monitor. On a basic level this just counts wheel rotations on an axle and concludes that if one wheel is turning fewer and fewer times over a given period that it is deflating.

I've had this light come on before after hitting a pothole a day after inflating my tyres correctly. I bought mine from a main dealer and they hadn't even set the correct pressures. Rears were like 2.1 2.4, fronts were 2.0, 2.2, a long way from what they should have been.

Put the correct pressures in, reset the Flat Tyre Monitor and drive off.

[creepy coupe]

It sounds like the tyre Monkey inflated them too pop the beads and didn't let any air back to adjust the pressures.

[C.J]

Thanks gents, your advice is greatly appreciated.

Looking at the tyres (running 60psi), they did look very stretched, with very little sidewall.

[creepy coupe]

I found the best all-round pressure on my 19" RF's was 38 rear 34 front. This helped reduce premature shoulder wear on the rears

[doughboy]

If the tyres were fitted and shipped from CM wheels, they will probably have been left at seating pressures by the tyre fitter.

I'm not sure who would fit wheels/tyres on a car without checking the pressures, and of course as responsible drivers (ahem) we should all check our tyre pressures weekly...

[C.J]

<holds hands up>

I know I should have checked. They are RFT from the 225 style alloy, so CM wheels are not to blame, as they were fitted by the last owner.

[makkan00]

Originally Posted by creepy coupe

I found the best all-round pressure on my 19" RF's was 38 rear 34 front. This helped reduce premature shoulder wear on the rears

And what is best all-round pressure for non-RFTs 19inch tyes?

[creepy coupe]

Originally Posted by makkan00

And what is best all-round pressure for non-RFTs 19inch tyes?

I ran with 34 front 235/35/19 36 rear 265/30/19.Falken 452's

[ed330D]

Originally Posted by AlwynMike

Look for the correct pressure on the plate next to the drivers door.
On my Touring, for your size tyres, it should be 39psi (2.7bar) front and 46psi (3.2bar) rear for normal usage - yours may be slightly different.

After running at 60psi (not only dangerous, but illegal as well!!), I would expect the steering to be heavier as you effectively have more tyre on the road as it isn't "ballooning".

Mike

Fully agree. Just a couple of things to add.

If you run with lower pressures than recommended by BMW there's a very real risk of abnormal shoulder wear.

When setting pressures it must be done on cold tyres, ie before you go out. It's useless to take the presssure after driving to a garage, and likewise at the tyre depot. I've found a 3psi difference between the pressure of a tyre that had been in the sun for a few hours and one in the shade, so try to pick a cloudy day or do it first thing in the morning. Of course you may be lucky enough to have a garage, so won't have this problem.

[C.J]

Well, I popped down to Tesco on the way home to top up the pressure on all 4.

To my horror, the fronts were now showing 14psi, and the rear 16psi. (After being sat for 9hrs at work).

Either the tyre place this morning misread my 60psi, and reduced it too low, or I have 4 tyres/alloys with a serious problem.

I've now topped them up to 37/40. I will keep an eye on them over the weekend.

[makkan00]

Originally Posted by creepy coupe

I ran with 34 front 235/35/19 36 rear 265/30/19.Falken 452's

Thanks. I'm running 32 all round and I thought it was high.
Will try your recommendation.

[djgandy]

Originally Posted by C.J

Well, I popped down to Tesco on the way home to top up the pressure on all 4.

To my horror, the fronts were now showing 14psi, and the rear 16psi. (After being sat for 9hrs at work).

Either the tyre place this morning misread my 60psi, and reduced it too low, or I have 4 tyres/alloys with a serious problem.

I've now topped them up to 37/40. I will keep an eye on them over the weekend.

Digital or analogue gauge? Find a good gauge! Digital garage ones are usually pretty accurate.

I borrowed someones analogue pump that read 10PSI high!

[zltm089]

60psi!!!!!!!!!!!!!!!!!!!! ....fcukin hell....thats some explosing pressure there!...lol...


you should be running around 36/ 38 for the fronts and about 40 for the rears....

since u got rft....up the rears by 42 actually...

[NH335i]

I could understand how a crazy person could set them to that.
Ive seen plenty of tires that say max psi 60 lbs.
So if someone read that and thought that meant set it to that, then viola.
Crazy person, driving on exploding tires.

[HighlandPete]

Originally Posted by C.J

Well, I popped down to Tesco on the way home to top up the pressure on all 4.

To my horror, the fronts were now showing 14psi, and the rear 16psi. (After being sat for 9hrs at work).

Either the tyre place this morning misread my 60psi, and reduced it too low, or I have 4 tyres/alloys with a serious problem.

I've now topped them up to 37/40. I will keep an eye on them over the weekend.

Sounds as if the tyre shop gauge was way off, if you later had 14 and 16psi.

As has been said, a warm tyre will increase in pressure, but only around 3 - 4psi this time of the year at low ambient temperatures, (unless you were burning rubber). So a big error this morning.

Best advice get a decent tyre gauge to keep a personal check on the actual pressures you are running. Even when you use an external source for pumping up tyres, use your gauge to set them to your known value.

HighlandPete