what caused this odd rear tire wear on my track setup?
12-20-2005, 03:21 PM
#1
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what caused this odd rear tire wear on my track setup?
Alignment was done before the start of the season with camber fairly even side-to-side front (-1.8) and back (-1.2), and 0 toe all around. what is rear thrust?
I rotated and flipped the tires, which are non-directional Falken Azenis Sports RT215 (discontinued), except for the last few street miles and this happened:
<img src="http://pictureposter.audiworld.com/10901/falken_azenis_sports_rt215.jpg">
I did run them on the street when the season was over. rear toe got knocked out? should I run toe in?, only in the rear? I was going to run a little toe out next season and the RT615 tires, but I don't want this to happen again. Or, is everything fine - but I shouldn't run these on the street. My winter setup is currently on and looks fine, but I haven't put many miles on them yet.
I rotated and flipped the tires, which are non-directional Falken Azenis Sports RT215 (discontinued), except for the last few street miles and this happened:
<img src="http://pictureposter.audiworld.com/10901/falken_azenis_sports_rt215.jpg">
I did run them on the street when the season was over. rear toe got knocked out? should I run toe in?, only in the rear? I was going to run a little toe out next season and the RT615 tires, but I don't want this to happen again. Or, is everything fine - but I shouldn't run these on the street. My winter setup is currently on and looks fine, but I haven't put many miles on them yet.
12-20-2005, 06:13 PM
#2
tires in back of pic look like they had too much pressure...
the tires in front, what was where? if the worn part was on the inside then it's just from running too much negative camber on the street, or excessive toe out on both wheels which is less likely. Thrust angle is the angle the rear tires point compared to the front, on a solid axle car it causes dog tracking if it's too great (car goes down the road sideways) but in IRS cars it's cured by proper toe settings, that's why you align the rear first. Your car doesn't have the signs of a bad thrust angle.
12-21-2005, 05:43 AM
#4
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Thread Starter
I agree. as they wore out, I noticed that running 36-38psi on the street is probably too much
for this 225/45/17 tire, which I've run in the past with S03s without issues. I run them as low as 28psi cold on the track, which get up to around 38-40psi hot. That change in temp probably means that I need to lose some weight 
The alignment specs had a range of 0 toe to just a little bit out. I said, absolutely no toe in. I always tell them that I'll pay an extra hour+ for even side-to-side neg camber and even toe all around. I don't mind paying for it to be done right.
the wear up front:
3/32" outside
2/32" middle
1/32" inside
the wear on the rears:
3/32" outside
0/32" middle
0/32" inside
I'm trying to find out what happened to that 2/32" in the middle of the rears, which run less neg camber. If anything, I would've thought the fronts would've looked like this, not the rears.
I guess I need to take a look at the current alignment specs, which I didn't want to pay to do until after winter.
The alignment specs had a range of 0 toe to just a little bit out. I said, absolutely no toe in. I always tell them that I'll pay an extra hour+ for even side-to-side neg camber and even toe all around. I don't mind paying for it to be done right.
the wear up front:
3/32" outside
2/32" middle
1/32" inside
the wear on the rears:
3/32" outside
0/32" middle
0/32" inside
I'm trying to find out what happened to that 2/32" in the middle of the rears, which run less neg camber. If anything, I would've thought the fronts would've looked like this, not the rears.
I guess I need to take a look at the current alignment specs, which I didn't want to pay to do until after winter.
12-21-2005, 04:34 PM
#6
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Camber my friend. Though this is NOT bad.
Tell me how many were street miles versus track miles. You want more negative camber at the track than on the street, so you may just need to live with this issue. BTW, did you get yourself a pyrometer yet? Great tool to determine what how much camber you need. 1.8 and 1.2 seems conservative and just about right though.
12-21-2005, 08:11 PM
#7
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Thread Starter
no pyrometer yet.
I was looking to get the Istook arms from you for up front, but my control arms haven't failed yet
Are there ones for the rear as well?
I think I'd like -2 or more up front and -1 or less in the rear. I don't tend to lean on the rears as much as I do steer with the rear. I probably scrubbed some of that rear tread off sliding around on those tires at the end of practice sessions and HPDEs.
It was mostly street miles (12-15k?) for the Azenis Sports. I think only 3 HPDE days and 2 Time Trials. I got more street miles and more track time out of my S03s. But, they got very greasy and slippery near the end of sessions. And my lap times were slower with the S03s.
Are there ones for the rear as well?
I think I'd like -2 or more up front and -1 or less in the rear. I don't tend to lean on the rears as much as I do steer with the rear. I probably scrubbed some of that rear tread off sliding around on those tires at the end of practice sessions and HPDEs.
It was mostly street miles (12-15k?) for the Azenis Sports. I think only 3 HPDE days and 2 Time Trials. I got more street miles and more track time out of my S03s. But, they got very greasy and slippery near the end of sessions. And my lap times were slower with the S03s.
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12-21-2005, 09:17 PM
#8
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Let me know
Let me know when you are ready for a nice pyrometer. I can get you a decent price. I am using the Longacre one, still $300 or so.
-2 in front will be too agressive on the street and -1 on the rear will be too little on the track. Compromises - they are tough. Let me know what you end up with, I have been playing with this for a while.
I only have the front arms. STaSIS makes decent rears, and CPP may as well. Don's fronts are VERY nice, and IMHO have slight advantage over CPP - castle nut, pin, etc. Though I am sure salt on PA and NJ roads will make them squeak after a year or two.
-2 in front will be too agressive on the street and -1 on the rear will be too little on the track. Compromises - they are tough. Let me know what you end up with, I have been playing with this for a while.
I only have the front arms. STaSIS makes decent rears, and CPP may as well. Don's fronts are VERY nice, and IMHO have slight advantage over CPP - castle nut, pin, etc. Though I am sure salt on PA and NJ roads will make them squeak after a year or two.
12-23-2005, 12:33 PM
#10
in my limited experence you are right to think about toe setings as the reason for
that type of wear. looks to me like the thrust angle is off in the rear and you are scrubing the the hell out of the tires. do the pressures on the rear rise more quicky then the front?
no question is camber a factor here but i'm thinking more about front rear wear diffrence and not so much about the side to side
imo before you run out and buy cpp make sure you are out of toe adjustment in the rear( if the worn tires are from the rear). I've had much better luck with alignments, that work for me, from a small race type shop.. just because the dealer has hunter rack with freakin lasers doesnt mean "adjustments" cant or wont be made to make the reading look "right" or "in spec".
no question is camber a factor here but i'm thinking more about front rear wear diffrence and not so much about the side to side
imo before you run out and buy cpp make sure you are out of toe adjustment in the rear( if the worn tires are from the rear). I've had much better luck with alignments, that work for me, from a small race type shop.. just because the dealer has hunter rack with freakin lasers doesnt mean "adjustments" cant or wont be made to make the reading look "right" or "in spec".