Agreed Tyre Pressures for 986

[Rav]

Hi All.

I just noted that my tyres are a little flat. I have been looking for the rather comical tyre pressure thread we had on here. I think i posted a picture of myself in my lether horse outfit! Anyway, i cant find that thread.

 

What did we agree the tyre pressures should be for 18" wheels please?

 

[mike597]

29/36  is the book. Some people find 30/31 rides a bit better at the front. 

[Rav]

Thanks @Mike597 - I've gone for 31 front and 36 rear and will write it down in my service book, so i have a record.

[EXY]

17 hours ago, Rav said:

Thanks @Mike597 - I've gone for 31 front and 36 rear and will write it down in my service book, so i have a record.

Did you check under the fuel flap, could save you some ink

[Ninesomething]

Easy to remember 2.0 and 2.5 bar. Mine had 29/31 in when I got it. I find it a bit squirmy at the back though with lower pressures.

[map]

2.0 bar all round - Toyo R888R or MichPSC  Get some warmth in them and they’re sublime on a dry surface.  R888Rs produced a lovely compliant ride on road. 

[PaulQ]

All down to personal preference. 

I find 29f a bit low, and 36r a bit high. 

[Lonewolfgjp]

I can’t really remember but I think I settled on 32f and 34r on my 18” on my 986 with new Goodyear eagles.

[Southy]

23 hours ago, Lonewolfgjp said:

I can’t really remember but I think I settled on 32f and 34r on my 18” on my 986 with new Goodyear eagles.

Thats what I run on Goodyear F1 asy 5's 

[Lonewolfgjp]

Great minds think a like 😂

[Cheddar Bob]

I'm on 29 front and 36 rear. 

Im not capable of driving fast enough to notice. 

[½cwt]

2.0bar front and 2.5bar rear (i.e. same as @Cheddar Bob above) per driver's manual.

[Ninesomething]

Several people above have advocated lower pressures. I'd like to get a better ride with lower pressures but it just feels too squirmy. Perhaps I'm not going fast enough to heat them up.

[½cwt]

6 minutes ago, JonSta said:

Several people above have advocated lower pressures. I'd like to get a better ride with lower pressures but it just feels too squirmy. Perhaps I'm not going fast enough to heat them up.

Manufacturers' pressures are when cold, so effectively a lower relative pressure when ambient is 5°C vs 22°C so it assumes that the hot working temp will also be lower when the ambient is lower....  It is always a compromise in road use, I just work on the basis that Porsche (or whoever) spent quite a bit if time testing the cars before finalising the specs in the manual.  When I did track days in my cars I always dropped the pressures to compensate for the higher running temp so higher hot pressure when on track.

[Ninesomething]

Hence, for a tyre filled to 32 psi, the approximation usually made is that within the range of normal atmospheric temperatures and pressures: Tyre pressure increases 1 psi for each 10 Fahrenheit degree increase in temperature, or conversely decreases 1 psi for each 10 Fahrenheit degree decrease in temperature and in SI units, tire pressure increases 1.1 kPa for each 1 Celsius degree increase in temperature, or conversely decreases 1.1 kPa for each 1 Celsius degree decrease in temperature. For tyres that need inflation greater than 32psi it might be easier to use a Rule of Thumb of 2% pressure change^[2] for a change of 10 degrees Fahrenheit. From the table below, one can see that these are only approximations:

 

According to this (wikipedia) and my dodgy maths the difference between 5 deg and 22 which it is today would be somewhere between 2 and 3 psi for a 30ish psi tyre. So inflating to manufacturers pressure would be 26/27 front 33/34 rear. Which would prob ride a fair bit nicer and once warm might be firm enough. I might try that.

[Lennym1984]

I run 28/36 on my Cayman and it feels pretty good.