Excessive Rear tire wear?
06-21-2020, 01:49 PM
#17
Burning Brakes
Thread Starter
Alignment isn’t something that is ‘set correctly,’ it’s a series of adjustments with ranges that have pros and cons for those settings. So you could have 5 identical 911s with different alignment settings that all behave differently, handle differently, and have different tire wear, and all alignment settings could still be ‘correct.’
Often, the factory recommendation for alignment will wear out the rear tires faster than a more conservative setting, so as the settings I have on my car.
Often, the factory recommendation for alignment will wear out the rear tires faster than a more conservative setting, so as the settings I have on my car.
06-21-2020, 02:13 PM
#19
RL Community Team
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06-21-2020, 02:21 PM
#20
Rennlist Member
Probably, when the 2002 2nd Gen 996 came out, in the door jamb where most PSI spec's are listed it had listed 36 PSI for the rear tires if there will be passengers in the rear seats.
If there is nothing heavy in the rear seats & Psi is 36 in rear tires the middle band of the rear tire will wear very Fast.
If there is nothing heavy in the rear seats & Psi is 36 in rear tires the middle band of the rear tire will wear very Fast.
06-21-2020, 02:45 PM
#21
Rennlist Member
Same with alignment. Just ‘having it done’ by a shop is like saying ‘a have new tires’ without any consideration to what type, brand, season, application.
You wouldn’t pick high heels to play basketball in, any more than getting your alignment done without telling the mechanic what type of alignment settings you prefer. Otherwise you could end up with an alignment setting that wears out or tires, or one where the handling isn’t very good.
Does that make sense?
06-21-2020, 05:18 PM
#22
Rennlist Member
Probably, when the 2002 2nd Gen 996 came out, in the door jamb where most PSI spec's are listed it had listed 36 PSI for the rear tires if there will be passengers in the rear seats.
If there is nothing heavy in the rear seats & Psi is 36 in rear tires the middle band of the rear tire will wear very Fast.
If there is nothing heavy in the rear seats & Psi is 36 in rear tires the middle band of the rear tire will wear very Fast.
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Elumere (06-24-2020)
06-21-2020, 06:11 PM
#24
Just a car guy
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220 is a relatively "soft" tire. Your wear is probably about right for that tire. What did you say 15,000 Km? Depending on how worn they actually are. I haven't seen a photo yet -so I can't provide my "professional" diagnosis. One thing that I note, is that you have seen more wear at the center of the tread. This is consistent with over inflation. I'd suggest backing off at least one or two psi in the future.
300-400 is my "happy" spot for street tires. Still enough grip to be safe and enough wear resistance for 20k-30k miles. This assumes all else is in good condition (alignment and pressures). For track use, a lower treadwear rating is preferred. That's where 220 and lower are best.
I have no tolerance for tires with large numbers for treadwear (generally 500 or above). There are some exceptions, but grip is usually sacrificed at the expense of tread-life. That's not a sacrifice I am willing to accept with my vehicles.
300-400 is my "happy" spot for street tires. Still enough grip to be safe and enough wear resistance for 20k-30k miles. This assumes all else is in good condition (alignment and pressures). For track use, a lower treadwear rating is preferred. That's where 220 and lower are best.
I have no tolerance for tires with large numbers for treadwear (generally 500 or above). There are some exceptions, but grip is usually sacrificed at the expense of tread-life. That's not a sacrifice I am willing to accept with my vehicles.
06-22-2020, 03:42 PM
#27
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06-23-2020, 07:27 AM
#28
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I went through this too Jim. You’ll see old posts from me about it. As others have said, the first thing is to ignore the recommended 44 psi for the rear, it wears out the centres like crazy. 38 psi seems to be the sweet spot for me, maybe even 36.
As far as alignment, again, I went down this road. The alignment shops machines all are built with a “range” where they are in the “green”. It’s actually a fairly wide range. If they are really paying attention, and few do...if green, good, never mind the number. Aa good friend is a automotive tech teacher and we just had this conversation the other night. Students rely on the technology of the machines, and don’t really understand what’s happening. He’s actually taken to forcing his students to learn to use strings, so they can actually see and understand what is happening, but I digress. My experiences is most shops, if they even look at the numbers, tend towards as close to zero toe as spec allows. On these cars, in my experience, this leads to excessive wear, particularly on the inside edge. Add a little extra toe (still within spec) and wear evened out for me at least.
I was getting 10-12,000 kms on a pair of rear tires (wear rating 220-340) prior to learning these things. My last set (Michelin PSS - 300 rating), are past 14,000 kms and still going, even with 3 full days of track use.
As far as alignment, again, I went down this road. The alignment shops machines all are built with a “range” where they are in the “green”. It’s actually a fairly wide range. If they are really paying attention, and few do...if green, good, never mind the number. Aa good friend is a automotive tech teacher and we just had this conversation the other night. Students rely on the technology of the machines, and don’t really understand what’s happening. He’s actually taken to forcing his students to learn to use strings, so they can actually see and understand what is happening, but I digress. My experiences is most shops, if they even look at the numbers, tend towards as close to zero toe as spec allows. On these cars, in my experience, this leads to excessive wear, particularly on the inside edge. Add a little extra toe (still within spec) and wear evened out for me at least.
I was getting 10-12,000 kms on a pair of rear tires (wear rating 220-340) prior to learning these things. My last set (Michelin PSS - 300 rating), are past 14,000 kms and still going, even with 3 full days of track use.
06-23-2020, 01:10 PM
#29
Burning Brakes
Thread Starter
Thanks.
I am not replacing the rear Rossos. As sticky as those tires were, this car is not driven anywhere near where we need those extreme performance levels. Instead I am going with a suggestion by Scott and getting Continental Extreme Contact DWS06 all around. When they do the alignment, I'll talk to them about adding toe. As for pressure, yes, I'll drop it a bit and just keep an eye on it. The car alternates between 1 passenger and 4 passengers.. On trips it is 4 people with cargo.
I am not replacing the rear Rossos. As sticky as those tires were, this car is not driven anywhere near where we need those extreme performance levels. Instead I am going with a suggestion by Scott and getting Continental Extreme Contact DWS06 all around. When they do the alignment, I'll talk to them about adding toe. As for pressure, yes, I'll drop it a bit and just keep an eye on it. The car alternates between 1 passenger and 4 passengers.. On trips it is 4 people with cargo.
06-23-2020, 01:35 PM
#30
Rennlist Member
I went through this too Jim. You’ll see old posts from me about it. As others have said, the first thing is to ignore the recommended 44 psi for the rear, it wears out the centres like crazy. 38 psi seems to be the sweet spot for me, maybe even 36.
As far as alignment, again, I went down this road. The alignment shops machines all are built with a “range” where they are in the “green”. It’s actually a fairly wide range. If they are really paying attention, and few do...if green, good, never mind the number. Aa good friend is a automotive tech teacher and we just had this conversation the other night. Students rely on the technology of the machines, and don’t really understand what’s happening. He’s actually taken to forcing his students to learn to use strings, so they can actually see and understand what is happening, but I digress. My experiences is most shops, if they even look at the numbers, tend towards as close to zero toe as spec allows. On these cars, in my experience, this leads to excessive wear, particularly on the inside edge. Add a little extra toe (still within spec) and wear evened out for me at least.
I was getting 10-12,000 kms on a pair of rear tires (wear rating 220-340) prior to learning these things. My last set (Michelin PSS - 300 rating), are past 14,000 kms and still going, even with 3 full days of track use.
As far as alignment, again, I went down this road. The alignment shops machines all are built with a “range” where they are in the “green”. It’s actually a fairly wide range. If they are really paying attention, and few do...if green, good, never mind the number. Aa good friend is a automotive tech teacher and we just had this conversation the other night. Students rely on the technology of the machines, and don’t really understand what’s happening. He’s actually taken to forcing his students to learn to use strings, so they can actually see and understand what is happening, but I digress. My experiences is most shops, if they even look at the numbers, tend towards as close to zero toe as spec allows. On these cars, in my experience, this leads to excessive wear, particularly on the inside edge. Add a little extra toe (still within spec) and wear evened out for me at least.
I was getting 10-12,000 kms on a pair of rear tires (wear rating 220-340) prior to learning these things. My last set (Michelin PSS - 300 rating), are past 14,000 kms and still going, even with 3 full days of track use.