Tyre Pressures
- Thread starter Cakesbaby
- Start date
At the summit of the picturesque fens
Whatever it says on the sticker on the inside of the door for the corresponding wheel size. 19" wheel pressures are published on the sticker.
I am convinced tyre pressures are published by the factory based on weight on each wheel for maximum handling and safety. Makes logical sense to me.
A RFT or a non-RFT have the same internal volume so the same amount of space to fill with air. The air supports the full weight of the car and that hasn't changed, so why change the amount of air?
I am convinced tyre pressures are published by the factory based on weight on each wheel for maximum handling and safety. Makes logical sense to me.
A RFT or a non-RFT have the same internal volume so the same amount of space to fill with air. The air supports the full weight of the car and that hasn't changed, so why change the amount of air?
Scottish Borders
If you look at the G29s Z4s running non runflat tyres they are in the 28-36 psi region..
I suspect the abnormally high pressures in the run flats was due to issues that may have occurred at very high speeds with that particular type of construction.
On the G29, like many cars they differ between low and sustained high speeds.
So after 6 years of E89 Zedding and at least 8 sets of different tyres I’d suggest on stock 19” sizes 32/34 and go 4-6 psi either way with a 2-4 front rear differential depending on make, style of driving etc…
I suspect the abnormally high pressures in the run flats was due to issues that may have occurred at very high speeds with that particular type of construction.
On the G29, like many cars they differ between low and sustained high speeds.
So after 6 years of E89 Zedding and at least 8 sets of different tyres I’d suggest on stock 19” sizes 32/34 and go 4-6 psi either way with a 2-4 front rear differential depending on make, style of driving etc…
I just looked at the sticker on my E89. The box for 'up to 2 passengers' is blank on the 19", and the other box for '2 passengers and luggage' is 34 psig front and 41 psig rear. It doesn't specify what 'type' of tyre is used; just size (225/35 and 255/30). Mine has actually got the wrong profile on the rear as they are 35!
So taking all the above replies into consideration and having done a multitude of very complicated calculations, taking into account atmospheric pressure at differing road temperatures, increases in pressure due to heat soak into the tyre at varying speeds and conditions, I have come up with the following recommendations:
34 psig for the fronts and 41 psig for the rears.
HTH
So taking all the above replies into consideration and having done a multitude of very complicated calculations, taking into account atmospheric pressure at differing road temperatures, increases in pressure due to heat soak into the tyre at varying speeds and conditions, I have come up with the following recommendations:
34 psig for the fronts and 41 psig for the rears.
HTH
The pressures published are for run flat tyres, which as we all know by now, have a very stiff sidewall, such they can operate safely without pressure, albeit for short distances at a restricted speed. You can use the same indicated pressures, but you may find that you will want to alter the pressures slightly depending on your driving style, I found that to give the same feel on turn in, I had to run a few psi higher on the front than indicated.
Chippie said:
I’m not advocating going lower but technically it’s not an issue..as you can see from this tyre pressure load rating table even at 26 psi the acceptable load rating comfortably exceeds the maximum load that an E89 can create.
So my 26 psi front would have a 28 psi rear..
The G29 runs 32 psi front and rear as a default setting for 17/18/19 tyres…
The tyre pressure setting is related to the overall suspension system…in most people’s views the Potenza run flat with a 19” rim at 42 psi was not a harmonious relationship.
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Pondrew said:
Your use of an English language construct implies I suggested that you could run 26 front 40 rear..
I did say 2-4 psi f/r differential..
G29 has zero f/r differential whist E89 has 6 psi…all BMW figures the same irrespective of tyre / rim size..
FWIW I’ve tried everything from 30/32 through to 40/42 with everything in between with 0,2,4 and 6 differentials….
I’ve tried 11 sets of tyres from 4 manufacturers on 17/18/19 wheels with square and asymmetrical set ups..
34/36 works acceptably in almost all cases…running 32/34 currently as the Moon has just passed Uranus which seems to have more logic than most pressure algorithms…
Wow there seems to be a lot of different views and suggestions. I had not considered my driving style which is quite sedate in the most part but has been known to be spirited up and down the M1/M6.
So would you agree a compromise of 34/38 would be suitable bearing in mind it stays under a 100 mph ??
So would you agree a compromise of 34/38 would be suitable bearing in mind it stays under a 100 mph ??
Good post - after being stopped on the tolpuddle bypass in my C63 at 01:30 doing over 135mph I had a discussion with a very reasonable police officer. When he stopped me I got out and said 'fair cop', he liked that I admitted it and the 'meeting' went as well as expected. He told me that I was driving well (apart from the speed) that I was capable and so was the car. He then went on to tell me that he would give me a ticket for 98 mph. This meant I had to pay a fine as you dont qualify for the speed awareness course at that speed. He then told me that once in excess of 100mph they can arrest and jail you on the spot before interview and charge the next day (nice criminal record) they will also seize the vehicle and you wont get it back be it a lambo or a Z4, personally owned or leased!!!!Pondrew said:EVERYBODY stays under 100mph otherwise they would have been banned from driving by now and the tyre choice/ pressures would be completely immaterial!mkinternet said:
Something to bear in mind...
San Francisco, CA