tyre pressures 993

[chris]

whats the best pressures to run 18" sport design wheels fitted on a 993 with Pirelli P zero's , the rears are 265's?

Migration info. Legacy thread was 21551

 

[Porsche]

here you are...

/images/migration/UploadedForumImages/911Tyres.JPG




Migration info. Legacy thread was 21561

 

[Porsche]

although porsche don't recommend changing sizes over OEM..

http://www.tyresave.co.uk/tyresize.html

have a play around with the tyre calc size...... in reality anything up to 3-5% over stand is fine.. only the speedo may be off..... although some say that the ABS may react differently on these older ABS systems (more so on the front)

overall I'm sure any 30 profile tyres on the rear will be a hard ride..

so you can get away with 265/35/18...........


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[chris]

Thanks Sundeep! ill try that

Cheers


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[Lurking Lawyer]

Apologies for dragging this up from the depths of history but it came up on doing a search and I thought it was worth commenting on my own personal experience of how much difference tyre pressures can make.

I bought my 993 Targa nearly 5 months ago. As much as I love it, I'd been a bit unimpressed with the high speed performance - it felt very nervous at anything about 80-85, especially on uneven surfaces. I did wonder if this was symptomatic of "tired" suspension or this was just how 993s handled (I don't have much experience of driving others, other than a few brief test drives before buying the one I ended up with). Either way, it didn't seen to handle very well at motorway speeds compared with the S2000 it replaced.

Turns out it was entirely a product of having over-inflated rears. When I first got it, I had checked the tyre pressures (a regular habit, coming from the S2000, which was VERY sensitive to tyres being even 0.5-1 psi out from the recommended pressure) and had found them all way out - having checked the manual's recommendations for 17" wheels, I inflated the fronts to 36 and the rears to 44.

I checked them again this morning before going for a run and noticed that two different PSIs are given for 17" wheels - one for winter and one for summer tyres. I thought I'd try the lower 36 PSI - what a difference! The car now feels altogether more "planted" and nowhere near as nervous as it did before. It's a revelation....

So, an object lesson to us all on the need to check regularly and keep tyre pressures where they should be!




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[Carrera]

L.L, I thought the 17" are meant to be 36psi front AND back? and the 18" should have 36Fr and 44 back?




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[Lurking Lawyer]

Quote: Originally posted by Butzi on 25 March 2007

L.L, I thought the 17" are meant to be 36psi front AND back? and the 18" should have 36Fr and 44 back?

Not entirely sure quite how I came to get 44 for the rears, Butzi. The manual is in the car in the garage at the moment so I can't go and check but, as I say, I think it gives different figures for 17s depending on whether you look at summer tyres or winter tyres. Somehow or other, I ended up using the wrong figure.

Anyway, it now has 36 all round and feels decidedly more predictable and stable than with 36 up front and 44 at the rears, which was really just the point of me posting - to point out how much difference to handling and the way it feels aberrant tyre pressures can create.


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[Used Porsche]

Lets be clear about this - 17's all round need 36/36 and this is because of two factors -

tyre width
comfort

18's need the 44 to make sure that the tread retains its shape against the centrifugal forces accross the wide tread at high speeds.

Comfort
17's are specified for Targas for two reasons:-

They are more comfortable for the occupants.
They don't transmit road bumps through to the glass roof structure as fiercely and therefore don't cause structural flexing as badly.

So 18 inch wheels are not recommended for Targas.

Which is why I have them.

Yes, they are set at 36/44 and after you drive the car for a week you forget that you used to think it was hard.
Bit like the blonde I met in Venice.
Ah well.

Migration info. Legacy thread was 127732