Tyre Pressure Guidance

[IRD]

Like so many others moved away from the dreaded runflats. Had some Michelin Pilot 4s’s fitted to my 3.5is last Thursday. The sizes are slightly different from standard. Fronts are 225/40/19s and the rears are 255/35/19s. Checked the pressures this afternoon and the garage has the fronts at 30psi and the rears at 35psi. Nothing like BMW’s recommended pressures. Any suggestions for suitable pressures gratefully received.

[MKZ4000]

I think it's a case of what works for you and a bit of trial and error.

I found that over inflation caused tramlining. I run 30 front and 32 rear.

[mr wilks]

On 18s or 19s I always found 32-34psi front & 34-36psi rear to be the best combination for comfort & steering feel.

[Lazza]

On my 35i with Uniroyal Rainsport 3 I use F36 R38. I’ve tried a bit less and a bit more but this feels like the sweet spot on these tyres.

[mr wilks]

On my 35i with Uniroyal Rainsport 3 I use F36 R38. I’ve tried a bit less and a bit more but this feels like the sweet spot on these tyres.

That's exactly it , different tyres & different spec cars you need to play around a little to find the pressures that work best

[IRD]

Thanks for your suggestions guys. Much appreciated. I have already noticed the new tyres are more comfortable and quieter.

[road warrior]

Thanks for your suggestions guys. Much appreciated. I have already noticed the new tyres are more comfortable and quieter.

Bloody hell.. 19s described as more comfortable. I can only imagine what the 19 rft were like...

[IRD]

Thanks for your suggestions guys. Much appreciated. I have already noticed the new tyres are more comfortable and quieter.

Bloody hell.. 19s described as more comfortable. I can only imagine what the 19 rft were like...

The runflats I have just got rid of were Pirelli Zeros and they weren’t too bad, certainly better than the Brigestones that I had on my E85. I had 108s on this and switched to Goodyears. I think the adaptive suspension on the E89 helps. Mind you it is early days having only tried the Michelin’s locally.

[IRD]

Thanks for your suggestions guys. Much appreciated. I have already noticed the new tyres are more comfortable and quieter.

Bloody hell.. 19s described as more comfortable. I can only imagine what the 19 rft were like...

The runflats I have just got rid of were Pirelli Zeros and they weren’t too bad, certainly better than the Brigestones that I had on my E85. I had 108s on this and switched to Goodyears. I think the adaptive suspension on the E89 helps. Mind you it is early days having only tried the Michelin’s locally.

Meant to finish with the thumbs up not the thumbs down!

[mr wilks]

Thanks for your suggestions guys. Much appreciated. I have already noticed the new tyres are more comfortable and quieter.

I'd be interested to hear your thoughts on the PS4S when not town driven.
Pay attention from 50mph - 80mph to roadnoise / tyre roar increasing with speed

[IRD]

Thanks for your suggestions guys. Much appreciated. I have already noticed the new tyres are more comfortable and quieter.

I'd be interested to hear your thoughts on the PS4S when not town driven.
Pay attention from 50mph - 80mph to roadnoise / tyre roar increasing with speed

Hi Andy. Glad you are still on the Forum. I read you recent post about the Michelins and I must admit it did make me hesitate. I only went for them after a lot of thought. I looked at getting some Goodyear’s but the size I needed for the rears is in short supply and consequently prices were unusually high. I got a really good deal on the Michelin’s so in the end I took the plunge. I’ll keep an eye on the noise levels over 50mph and let you know.
Cheers

[Busterboo]

I think it's a case of what works for you and a bit of trial and error.

I found that over inflation caused tramlining. I run 30 front and 32 rear.

You obviously only use the car to do the shopping, so those pressures are just right!

[Busterboo]

On 18s or 19s I always found 32-34psi front & 34-36psi rear to be the best combination for comfort & steering feel.

Are you running your 911 (with its beautiful lobster claws) on those pressures? I'll bet you're not.

If you are, you're missing a trick, because it'll be more agile on the Porsche recommended 36 front & 44 rear and your rears will last much longer.

(Is it a coincidence, I wonder, that BMW recommend the same pressures for their 3-litre Z4s?)

[mr wilks]

On 18s or 19s I always found 32-34psi front & 34-36psi rear to be the best combination for comfort & steering feel.

Are you running your 911 (with its beautiful lobster claws) on those pressures? I'll bet you're not.

If you are, you're missing a trick, because it'll be more agile on the Porsche recommended 36 front & 44 rear and your rears will last much longer.

(Is it a coincidence, I wonder, that BMW recommend the same pressures for their 3-litre Z4s?)

Currently ( Vred Vorti R ) on 36psi f 40psi r ( 235 35 19) & no plans to change that , drives fine & feels right .
As for any coincidence with Bmw one has a rear engine & much bigger tyres & wider rims ( 11j with 305 30 19 ) both possible reasons for the 44psi recommendation , a 19 inch runflat 255 30 19 on a 9j rim only needs looking at to know its going to offer little by way of comfort or rim protection & pretty sure this "mistake" has been rectified on the G29

[Busterboo]

On 18s or 19s I always found 32-34psi front & 34-36psi rear to be the best combination for comfort & steering feel.

Are you running your 911 (with its beautiful lobster claws) on those pressures? I'll bet you're not.

If you are, you're missing a trick, because it'll be more agile on the Porsche recommended 36 front & 44 rear and your rears will last much longer.

(Is it a coincidence, I wonder, that BMW recommend the same pressures for their 3-litre Z4s?)

Currently ( Vred Vorti R ) on 36psi f 40psi r ( 235 35 19) & no plans to change that , drives fine & feels right .
As for any coincidence with Bmw one has a rear engine & much bigger tyres & wider rims ( 11j with 305 30 19 ) both possible reasons for the 44psi recommendation , a 19 inch runflat 255 30 19 on a 9j rim only needs looking at to know its going to offer little by way of comfort or rim protection & pretty sure this "mistake" has been rectified on the G29

I assume you inherited the Vredesteins. When the time comes for a change - the sooner, the better - buy some Pirelli P Zero Rosso and discover how good your 911 is.

Yes, I know the Vreds review* well and pound for pound are good tyres, but they're certainly not as good as the best and, on a brilliant Porsche like yours - the last of the short wheelbase 911s - why compromise? To save money and spoil the car?

*Tyre reviews and their pseudo-scientific data are one of the biggest dishonesties of the car world - and Heaven knows there are plenty.

As for pressures on Z4s, from replies on the forum, it looks as if people are frightened of 'high' ones. Perhaps because so many are on fragile 19" wheels or because they have no experience of one of the most critical features of performance, I don't know. But they're missing a key element of the car's performance.