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YOUR RESEARCHtyre pressures
Leading reported evidence
Replace rears at 18,500 k and continue
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Read evidence and context
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Performed · outcome unconfirmed
Replaced the rears at 18,500 K and continue to run 44 on the theory that the next set of tires will be a complete front/rear change.....
Leading evidence: 'Replace rears at 18,500 k and continue' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Recommend by michelin as a starting point' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
I run 35/43 street and 32/36 track on my 18s (with 285s on the rear and 225 on the front).
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Performed · outcome unconfirmed
I run 36/44 on 18" wheels, and the rear tire wear suggested 44 was overinflated.
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Performed · outcome unconfirmed
No suspension changes and I run stock pressure on the street and track.
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Performed · outcome unconfirmed
Nonetheless, I run stock tire pressures on my street tires (36/44) and have never had any high speed instability on the street.
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Suggestion
I changed over to PSS9's and put as much negative camber in the front as could get without buying camber plates and the car is very neutral with a hint of understeer on a couple of corners at Thunderhill.
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Rennlist: 1 discussions
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hi all,what tyre pressures are u using on your cars?and why if differen from what porsche states.
please state if your wheels are 17 or 18 inch.
i have 18 5 spoke carrera style 225 and 285
thanks
I also use the Porsche recommended pressures. I only change them on the track.
Your cars high speed instability is puzzling as you state that it was cured by a minimal change in tire pressures. I'd make sure that your alignment is correct. What tires do you have on your car?
Viken,
Thanks! I read that as the spare should be 36 or if you had a C4 or C4s it should be 36
The strange thing is that when I checked them that was what they were set at by the dealer. Oh well, I guess I will have to adjust them now and see what happens! Hopefully it will reduce some of the tramlining effect that I get.
Thanks!
Barry
I run 36/44 on 18" wheels, and the rear tire wear suggested 44 was overinflated. The fronts are perfect.
Replaced the rears at 18,500 K and continue to run 44 on the theory that the next set of tires will be a complete front/rear change.....
carbonissimo,
I used to run with my stock Pirelli's on the track and start out with cold tire pressures of 32(f) and 36(r) and then adjusted them as they got hot. With the stock suspension (this will depend on your suspension and alignment settings) and alignment settings, the car would understeer and I could not dial this out with tire pressure changes. I changed over to PSS9's and put as much negative camber in the front as could get without buying camber plates and the car is very neutral with a hint of understeer on a couple of corners at Thunderhill. I've since switched to MPSC's for track use and I use the cold temp's recommended by Michelin as a starting point.
Nonetheless, I run stock tire pressures on my street tires (36/44) and have never had any high speed instability on the street. There are many posts that have stated that Porsche tends to recommend high tire pressures with regards to comfort. I can't imagine that they would design a car where a couple of pounds of tire pressure would make it dangerous at triple digit speeds. So...are you running N-rated tires and have you had any suspension upgrades and alignment changes?
