997 tyre pressures?

[paulfcraven]

A very experienced 911 owner has told me that the book tyre pressures on my 997C2 for local running on A and B roads and keeping within posted limits are too high and a better ride can be had by dropping pressures by 5lbs(F) and 6lbs(R). I have tried this and he is right. The book figures on a 997 C2 18" wheels are 37lbs(F) and 44lbs(R) which would seem necessary for continued high speed travel on Autobahn and track days but not running about in rural N.Yorks. What do you think?

 

[Hubertus]

Sounds spot on old chap. Fiddled times many with pressures and ended up at 32lbs. front and 38lbs. rear. which suits me fine. But beware of adjusting pressures in winter, at 5C you should be around 2lbs. down on the above.
Cheers

 

[paulfcraven]

Thank you John for your confirmation and your tip for winter. Off to Silverstone tomorrow so they are back up to normal.

 

[DSM]

ORIGINAL: paulfcraven

A very experienced 911 owner has told me that the book tyre pressures on my 997C2 for local running on A and B roads and keeping within posted limits are too high and a better ride can be had by dropping pressures by 5lbs(F) and 6lbs(R). I have tried this and he is right. The book figures on a 997 C2 18" wheels are 37lbs(F) and 44lbs(R) which would seem necessary for continued high speed travel on Autobahn and track days but not running about in rural N.Yorks. What do you think?

My book figures, at ambient, are 34 and 40, not 37 and 44. Are you quoting hot pressures?

 

[MarcBC]

On my 19" 235/305s I run 37 / 44 which are the recommended pressures for a car with one driver and luggage - or one me!

 

[DSM]

Not in my handbook! Partly loaded, up to two people, no luggage 34/40.

Fully loaded two or more people + luggage, then the higher pressure.

 

[MarcBC]

ORIGINAL: DSM

Not in my handbook! Partly loaded, up to two people, no luggage 34/40.

Fully loaded two or more people + luggage, then the higher pressure.

The pressure lable I am reading from is on the driver's side door frame. It may be for two people, I cannot remember. I do know that I am almost two people however, []

 

[DSM]

ORIGINAL: MarcBC

ORIGINAL: DSM

Not in my handbook! Partly loaded, up to two people, no luggage 34/40.

Fully loaded two or more people + luggage, then the higher pressure.

The pressure lable I am reading from is on the driver's side door frame. It may be for two people, I cannot remember. I do know that I am almost two people however, []

Ah well, as long as you're not more than two and don't carry luggage you should be OK!

I'm probably less than an average person and rarely let anyone else in with me so I might try lower!!!

 

[Alex L]

ORIGINAL: paulfcraven

A very experienced 911 owner has told me that the book tyre pressures on my 997C2 for local running on A and B roads and keeping within posted limits are too high and a better ride can be had by dropping pressures by 5lbs(F) and 6lbs(R). I have tried this and he is right. The book figures on a 997 C2 18" wheels are 37lbs(F) and 44lbs(R) which would seem necessary for continued high speed travel on Autobahn and track days but not running about in rural N.Yorks. What do you think?

If you reduce pressure by that many psi then won't your fuel economy really suffer as the friction with the road will be much higher? Plus won't your tyre roar be louder on motorways?!

In fact, if I dropped mine by 5 or 6psi then my TPMS alarms would all go off!

If anything I tend to go slightly above the recommended 'cold' values (33/39psi F/R on a Turbo) and I don't have any problems with ride.

 

[paulfcraven]

The pressures for 18" wheels for all loading conditions are 2.5bar(f) and 3.0(r). 19" wheels are 2.3 and 2.7 respectively with two occupants, but 2.5 and 3.0, two up with luggage. My original query was about softening the ride on bumpy N.Yorks B roads and lowering the pressures did improve things without noticeably increasing the tyre temperatures(non-scientific measurement) or increasing fuel consumption.

 

[paulstevens]

Guys, I would be very wary of running lower than advised pressures. I am sure I have read that running low pressures will work the tyre walls harder, increasing temperatures and therefore possibly moving towards wall failure. Is there a tyre guru out there to confirm my thoughts?

Paul