Non-RFT pressures

Lazza · Post by **Lazza** » Sat Nov 17, 2018 2:20 pm

Ok, without wanting to start a new bun-fight, I’m going to ask “that” question

What is the recommended tyre pressure for non-RFT on my E89 35i? The RF pressures seem way too high so I was thinking around F34 R36. This is on Uniroyal Rainsport 3. Does that seem about right?

Gazza51 · Post by **Gazza51** » Sat Nov 17, 2018 4:13 pm

I changed from RFT’s and pump to 2.2bar (32psi)

Lazza · Post by **Lazza** » Sat Nov 17, 2018 7:51 pm

Gazza51 wrote: ↑Sat Nov 17, 2018 4:13 pm I changed from RFT’s and pump to 2.2bar (32psi)

Same front and rear?

Gazza51 · Post by **Gazza51** » Sat Nov 17, 2018 8:54 pm

Lazza wrote: ↑Sat Nov 17, 2018 7:51 pm
Gazza51 wrote: ↑Sat Nov 17, 2018 4:13 pm I changed from RFT’s and pump to 2.2bar (32psi)
Same front and rear?

Yes, you can go higher on the rear if you carry a boot full of stuff

Lazza · Post by **Lazza** » Sat Nov 17, 2018 9:59 pm

The only thing I keep in the boot is the roof

montymog · Post by **montymog** » Sat Nov 17, 2018 10:22 pm

tyre presure is load dependant as your not altering the loading just changing the tyre use the guide on your door pillar

mr wilks · Post by **mr wilks** » Sat Nov 17, 2018 10:46 pm

Lazza wrote: ↑Sat Nov 17, 2018 2:20 pm Ok, without wanting to start a new bun-fight, I’m going to ask “that” question

What is the recommended tyre pressure for non-RFT on my E89 35i? The RF pressures seem way too high so I was thinking around F34 R36. This is on Uniroyal Rainsport 3. Does that seem about right?

Id say bang on perfection with those numbers whether 18inch or 19inch , may vary a little depending on tyre brand / kind of driving you mainly do & also Re Se , Mpsort or aftermarket springs but i would expect F34 R36 to satisfy 99% of Z owners 99% of the time .
you could play around from there up or down but not by much

Lazza · Post by **Lazza** » Sat Nov 17, 2018 11:03 pm

Thanks Mr Wilks. A good place to start then. I’m happy to tweak them to find my own personal sweet spot, I just wanted a good starting point

montymog wrote: ↑Sat Nov 17, 2018 10:22 pm tyre presure is load dependant as your not altering the loading just changing the tyre use the guide on your door pillar

While this is true, run-flats have different characteristics and requirements from standard tyres. No car the size of a Z4 should need over 40psi in non RFs!

Busterboo · Post by **Busterboo** » Wed Nov 28, 2018 3:26 am

Lazza wrote: ↑Sat Nov 17, 2018 11:03 pm No car the size of a Z4 should need over 40psi in non RFs!

BMW disagree with you. Read the label on your B pillar and you'll see.

Busterboo · Post by **Busterboo** » Wed Nov 28, 2018 3:34 am

mr wilks wrote: ↑Sat Nov 17, 2018 10:46 pm ... i would expect F34 R36 to satisfy 99% of Z owners 99% of the time ...
you could play around from there up or down but not by much.

F34 is a couple of pounds too low, but R36 is more than 7 out!

Don't believe me? Then ask Michelin: https://www.michelin.co.uk/tyres/car-ty ... 40-18-88-W

Tinker15 · Post by **Tinker15** » Wed Nov 28, 2018 10:37 am

Busterboo wrote: ↑Wed Nov 28, 2018 3:34 am
mr wilks wrote: ↑Sat Nov 17, 2018 10:46 pm ... i would expect F34 R36 to satisfy 99% of Z owners 99% of the time ...
you could play around from there up or down but not by much.
F34 is a couple of pounds too low, but R36 is more than 7 out!

Don't believe me? Then ask Michelin: https://www.michelin.co.uk/tyres/car-ty ... 40-18-88-W

I might be being thick but if you follow the link it says FRONT 36.26 (36.26)PSI and REAR 39.16 (43.51)PSI. So is it 39 or 43?

Busterboo · Post by **Busterboo** » Wed Nov 28, 2018 11:21 am

If you click on the arrows, you'll see Michelin's figures are unladen and laden. They're the same front and higher rear, of course.

Unladen or not, however, they're significantly higher than recommendations in this thread.

The bottom line is that most people drive round on tyres that are too soft.

Tinker15 · Post by **Tinker15** » Wed Nov 28, 2018 11:44 am

The cross/arrows don’t work on an iPad. Checking on my MacBook it actually says ‘normal use’ which with the limited ability to carry massive amounts of luggage is probably what most people would use. I agree it is higher than some have mentioned on this thread but not as high as that recommended for run flats.

Busterboo · Post by **Busterboo** » Wed Nov 28, 2018 12:36 pm

Many people's logic seems to be, 'I've ditched the horrible & hard runflats. Now I can run 'normal' tyres at lower pressures.' And they then often run them too soft - 32 & 34 or 34 & 36 are quite common.

All I'm suggesting is to follow tyre manufacturers' or BMW's guidelines.

Phoenixboy · Post by **Phoenixboy** » Wed Nov 28, 2018 4:25 pm

Busterboo wrote: ↑Wed Nov 28, 2018 12:36 pm Many people's logic seems to be, 'I've ditched the horrible & hard runflats. Now I can run 'normal' tyres at lower pressures.' And they then often run them too soft - 32 & 34 or 34 & 36 are quite common.

All I'm suggesting is to follow tyre manufacturers' or BMW's guidelines.

so your suggesting running the same pressures on non runflats as runflats.
the info on the door pillar is for runflats, which I assume if you follow bmw guidelines, will also be for runflats, as they are unlikely to offer advise on tyres they don't fit to the car.

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