red targa

Hi All,

Just to share a surprising experience. My rear S03's are wearing out at only 8,000 mi of street driving (no track).

The front tires look like they will last much longer time.

Usually I inflate them at 36 psi all around. I have PSS9's installed (firmness setting at 8 or 9). The car has been lowered to about RS height.

Weather conditions here is about 36 deg in summer and 15 deg in winter.

Does anyone else have similar experience? I am going to use a tire gage to measure the tread depth later today.

C2MED

I use SO2 and it's lasting much better than Pirelli I had previously. The front tends to last twice as long.

JohnM

How you drive the car will have quite an influence Some have reported getting through rear tyres in only 4k miles.

FWIW, I do not think it is a good idea to run the PSS-9 softer than 6 for the rear dampers, however crap the roads. At 7 or softer body movement is underdamped, one consequence of which is that the car slides at the rear much earlier than it otherwise would under fast entry to turns or rapid changes of direction due to the load variations on the tyre caused by the movement of the body. It is generally benign and can be quite entertaining, but it is definitely not the fastest way to get around and if you drive "enthusiastically" it will eat your tyres. Body control at settings of 8 or 9 on the PSS-9 setup is worse than the standard suspension, 7 is similar to standard. At 6 it improves quite a bit, and 5 is better again. The front is a lot less sensitive and does not need to be set as firm for road use.

Jack Ennuste

8000 Mi for rears is relatively good result -- my opinion.

Robin 993DX

John,

I hate to tell you this, but I think your driver have been taking your 993 out when you are out of town....



BTW, I met up with John and his friend James in Taipei last month (Prior to tha SARS out break). He treated me to lunch and we had a great time talking about 993s.

maurice97C2S

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by JohnM:
<strong>FWIW, I do not think it is a good idea to run the PSS-9 softer than 6 for the rear dampers, however crap the roads. At 7 or softer body movement is underdamped, one consequence of which is that the car slides at the rear much earlier than it otherwise would under fast entry to turns or rapid changes of direction due to the load variations on the tyre caused by the movement of the body. It is generally benign and can be quite entertaining, but it is definitely not the fastest way to get around and if you drive "enthusiastically" it will eat your tyres. Body control at settings of 8 or 9 on the PSS-9 setup is worse than the standard suspension, 7 is similar to standard. At 6 it improves quite a bit, and 5 is better again. The front is a lot less sensitive and does not need to be set as firm for road use.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Hi John - this is rather interesting - I run mine on 6 all round (with monoballs and 18s/PZeros) - at the last Bruntingthorpe do I was 'exploring the limits' as they say, and on this 65-70mph right hander with surface changes the back went, absolutely like lighting! I was on full opp lock in a millisecond or so, but the rear just kept going, on part throttle .... Earlier it had been wet, and the car would understeer on turn in, but come round on the throttle happily - I was rather surprised by this behaviour in the dry. Checked tyre pressures, roll bar clearances etc.

What has sent you on this path? Lots of track days?

Cheers, Maurice

ca993twin

I started a thread on the turbo forum about excessive tire wear. Its a subject that I find very curious. My suspicions are that there is a rear toe alignment issue with the cars seeing unusually high rear tire wear rates. My only point of reference is that I bought my TT 5 months ago with S03s on the rear. They were at about 40% at that time. I have added about 3,000 miles, and the rear tires are now at about 20%. If that estimate is accurate, I should see about 15,000 miles or so on new rear tires. I don't track the car, but am fairly agressive on on ramps and curves. My car has ROW springs and stock shocks.

Any thoughts on this?

JohnM

Hi Maurice,

My comments are based on the feel of the car, road and track - I've not lost the car on either (famous last words ) but vehicle body control is a bit of a hobby horse of mine, which is what set me off on the PSS-9 route in the first place (the std suspension is way too soft for my liking). I've done a few miles with various PSS-9 setups now, specifically:

12,000 miles PSS-9 + std anti-roll bars
8,000 miles PSS-9 + RS bars (middle/middle)
15,000 miles PSS-9 + RS bars + monoballs

and explored various damper settings in the course of that. I settled on 6F/6R fairly early on, but lately tried 7F/7R for a few days after my brother started griping about dental bills . It was so poor in comparison to 6/6 that I tried setting the rear to 5, which was much better. The grip limit with 5 at the rear is higher, you can really lean on the rear end through and out of the corners, but if you hit a bad bump mid corner when pressing on you need to be very quick with the correction. You can certainly feel the extra momentum that builds up at the rear from the higher cornering speeds.

The rear springs on the PSS-9 are fairly stiff, so naturally need damping to match if the dynamics of the body are to be kept under control. I just find that at 7 or softer there is too much rear end over/undershoot in transitions, which disappears at stiffer settings. Going stiffer than 5 becomes increasingly problematic on poor road surfaces, at least with 18" wheels, as the tyres leave the ground too much so in corners you travel outwards nearly as much as forwards.

Q

Interesting timing of this thread.
I had my Boxster S up on the hoist today.
Whilst it was up, I checked the wear on my SO3's
They are only 5000km [3100mls] old, but I have lowered it 36mm, so am conscious of the 1.5 deg neg camber.

Fronts are [surprisingly] VERY good for 5000km
The rears were the surprise. They were twice as worn <img border="0" title="" alt="[Eek!]" src="eek.gif" />

The handling of this car is well sorted, although I do tend to drive it like the 993
Slow in, steer with the throttle, HARD OUT.

.......and that is the bottom line.
The rears take so much more lateral load

Look on the bright side....
If we drove V8 utes, we would be complaining of 4 worn tyres from big understeer and power on oversteer <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

LOL

User 4621

John L,

I recommend cornering much faster. This will help your fronts catch up to your rears. <img border="0" title="" alt="[Wink]" src="wink.gif" />

Are the insides of your rear tires more worn than the outsides? This can be common for people who have set too much negative camber for for the type of driving they do. (you mentioned having PSS-9's but no track time)

red targa

Dear All,

Thanks for the comments and suggestions.

Finally got time to measure the thread, and I found:

Front tires have about 7 mm of thread left (inside and out)

Rear tires have about 3mm on the outsides and 2.5 mm on the inside.

This might concurr with What Pete mentioned in his post about Neg chamber. I am thinking about raising my ride height a bit (what do you think Robin?), so I will have the alignment done again.

I don't track, but on morning Golf runs (5-6 AM), I tend to drive quite enthusiastically.

I might have to change the tires soon, because it rains quite a bit here. What's the minimum thread needed before replacement?

BTW, John M: I can't imagine driving with 6F/6R here, but I might go back to 8F/8R. Did you notice much difference in ride quality after you added monoballs?

Robin: It was fun meeting you in Taipei. Hello from James too.

Thanks,