Tyre pressure non run flat
- Thread starter peter2704
- Start date
peter2704 said:
To my mind the pressure is the pressure regardless of the whether run flats or not since the primary function of the air in tyres is support the load of the car which remains a constant. I'm also running standard tyres but I have stuck to the BMW recommended pressures.
This./\Fady said:
Pressures should only be changed for different internal volumes of tyres IMO, not whether they are RFTs or not.
As said, the bit of air inside the tyres supports the whole weight of the car. The manufacturer went to great lengths (presumably) to determine what those should be for a given volume of space inside the tyres.
Why anyone would decide they know better is a strange phenomenon exclusive to car forums IME.
Always makes me laugh when the 'forum experts' ask what make of tyre you have. It makes sod-all difference.
I ran my first set of rear nonrft at recommended 42 psi.
The rear would skip bumps and later with wheel off i could see the crown of the tyre wearing more than the edge.
Now run 40psi rear and get even wear.
Same at the front use 40psi get even wear which to me it means the load is spread even across the tyre.
Theses tyres are GY asym 5 now.
Just experiment.
The rear would skip bumps and later with wheel off i could see the crown of the tyre wearing more than the edge.
Now run 40psi rear and get even wear.
Same at the front use 40psi get even wear which to me it means the load is spread even across the tyre.
Theses tyres are GY asym 5 now.
Just experiment.
Exactly , some complete ballaux posted in this threadflybobbie said:
why would any end user assume the big names have every corner covered , their mistakes small or large are legendary & even worse repetitive . Don't be a sheep following the herd , there are alternative tyres, tyre pressures , oil brands & possibly the biggest insult to a car owners intelligence :evil: alternative service regimes than they stipulate as fact .
So, there's your choice, fellow Z4 owners: follow BMW or mr wilks. Easy, really.mr wilks said:Exactly , some complete ballaux posted in this thread
Don't be a sheep following the herd , there are alternative tyres, tyre pressures , oil brands & possibly the biggest insult to a car owners intelligence :evil: alternative service regimes than they stipulate as fact .
Like the light aircraft we fly.
Aircraft were designed around 1950's technology with tyres made in the 70's.
Tyre pressures quoted in manual.
Modern tyres have different ply ratings and manufacturers, probably due liability and original certification, offer no new tyre pressures.
So we run probably 10 psi more than old manual figures.
The old tyre pressures the tyres look well deflated.
Aircraft were designed around 1950's technology with tyres made in the 70's.
Tyre pressures quoted in manual.
Modern tyres have different ply ratings and manufacturers, probably due liability and original certification, offer no new tyre pressures.
So we run probably 10 psi more than old manual figures.
The old tyre pressures the tyres look well deflated.
Busterboo said:So, there's your choice, fellow Z4 owners: follow BMW or mr wilks. Easy, really.mr wilks said:Exactly , some complete ballaux posted in this thread
Don't be a sheep following the herd , there are alternative tyres, tyre pressures , oil brands & possibly the biggest insult to a car owners intelligence :evil: alternative service regimes than they stipulate as fact .
if the big names never made mistakes I'd follow your thought process but as anyone with the slightest interest in cars ( & particular germanic ones) should know is that unfortunately for the end user we don't always get faultfree or even flawfree cars .Tyre sizes are a perfect example of a mistake finally acknowledged & rectified.
Through the 90s to 2020s Bmw persisted with 30 + 35 profile + RFTs on 19s whilst MB & Audi did not .
Now Bmw have upped their profiles like their rivals , why didn't the rivals change theirs to what Bmw were fitting ? :wink:
You're a salesmans dream Mr Bb
matsmith749
Active member
I had to laugh at this thread 
thanks all.
Tyre pressure for run flats / non run flats isn't the same - even the manufacturers keep changing their minds!
Tyre construction plays a big part, and in the early days of run flats (which is what your label in the door jam is using) were nonsense & soon revised in later years. Of course your sticker doesn't change just because the manufacturer figured things out better after the fact.
If you need proof, there are some cars available that have run flats fitted to the base level cars, and non run flats fitted to the performance option (look at the 2 series BMW 220 vs m240i for example). The tyres have different psi values.
Most people go with the knowledge gained from a large group of users testing this out (from another forum) & combine that with the shift in attitude from BMW on more recent cars - which is on 19" rims at 38 psi rear, 34psi front.
I only paid attention to the 19" rim pressures as that is what I have
thanks all.Tyre pressure for run flats / non run flats isn't the same - even the manufacturers keep changing their minds!
Tyre construction plays a big part, and in the early days of run flats (which is what your label in the door jam is using) were nonsense & soon revised in later years. Of course your sticker doesn't change just because the manufacturer figured things out better after the fact.
If you need proof, there are some cars available that have run flats fitted to the base level cars, and non run flats fitted to the performance option (look at the 2 series BMW 220 vs m240i for example). The tyres have different psi values.
Most people go with the knowledge gained from a large group of users testing this out (from another forum) & combine that with the shift in attitude from BMW on more recent cars - which is on 19" rims at 38 psi rear, 34psi front.
I only paid attention to the 19" rim pressures as that is what I have