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Registered
Join Date: Jul 2000
Location: Agoura Hills, Ca.
Posts: 1,651
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When is a tyre too worn?
So last week I did a pirouette around a round-a-bout and scared myself and the ease with which the tyres let go.
This weekend I'm following some type of Honda thingy with the big can pipes hanging off the back. Anyhow we are doing a bit of chasey as we come into a left sweeper (driving left hand side of the road in HK). Before the sweeper we are descending, then nearly into a 90 degree sweeper. He goes in and accelerates nicely out. I'm only a few metres behind and follow his line. I suddenly feel the front tyres letting go, feeling strong understeer. Then the back starts letting go. I put a little more gass into it and snake my way straight, but geez I could drive my Mitsubishi beater better thru that corner. So back to my question, how much tread before you turf (throw) your tyres out? Or do I have some serious problem elsewhere? I can't believe a corner balance will make all the difference but am I wrong? I've got new - turbo tie rods, Bilstein shocks, but stock bars. I've had the same type of problem with my other tyres but they too were pretty worn. How much is too much?
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'87 911 3.2ltr Cab. ROW (sold  )'90 964 3.8 ltr C4 Coupe (P-Dealer built, track prep'd, sold ) )OMYG..I'm Porscheless |
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03-16-2003, 10:58 PM
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911 user
Join Date: Sep 2001
Location: East of Eden, West of the Sun
Posts: 2,411
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My own guideline is about 2mm of thread.
What I've found is that as the tyres wear their handling and roadholding characteristics change as the rears are wearing faster, this is more noticable on some surfaces than others and changes again for wet and dry conditions. In my non-technical way I would describe it as having stickier rears in the dry and stickier fronts in the wet, I've found this especially noticable with Pirelli assimetricos much less with Dunlops and Eagles. One can compensate a little for this by fiddling with tyre pressures. However, I don't think this is what you are describing. Have the car checked out by a good shop that does race prep on 911s. A car that acts like that takes all the fun out of ownership,
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Where once the giants walked now Mickey Mouse is king. My other car is also a Porsche. |
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03-16-2003, 11:14 PM
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Non Compos Mentis
Join Date: May 2001
Location: Off the grid- Almost
Posts: 10,597
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How old are the tires? They will harden with age.
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03-17-2003, 07:11 AM
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Back in the saddle again
Join Date: Oct 2001
Location: Central TX west of Houston
Posts: 55,988
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probably tires, but yes a corner balance can make a huge difference. Imagine if the balance is off, then 2 tires are doing most of the work, and even then it is the two opposite tires (like left front right rear). Your car could sit completely level and still be out of balance. Not saying that is the problem, just that it could be.
What about alignment?? Is it aggressive or stock, because the stock alignment is pretty timid, basically 0 camber front and just a hair negative in the rear.
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Steve '08 Boxster RS60 Spyder #0099/1960 - never named a car before, but this is Charlotte. '88 targa SOLD 2004 - gone but not forgotten
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03-17-2003, 07:16 AM
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Registered
Join Date: Oct 2000
Posts: 3,632
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More important if your tires are nearing ten years old even though they look good they compound is probably dried up especialy pirelli tires, Kevin
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03-17-2003, 08:14 AM
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