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Old 05-23-2009, 06:42 PM   #1
Loren
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Tire Wear Analysis

I've been noticing some of my tires look pretty thin from certain angles lately, and someone commented at the last autocross I went to (after I posted the 5th fastest street tire time of the day, within .3 of the fastest) that "man, those tires are DONE!"... so I thought it was about time I did something about it.

I'm in an awkward tire situation. I had a set of four new T1R's (215/45-15... about the same width as a "normal" 205) about 12 months ago, but one of them got mangled on the road (piece of a utility knife blade cut a 3" long gash across the tread) back in October. I wasn't thrilled with the T1R's, so I bought a pair of Star Specs (195/55-15) for the front. Sooooo...

What I have now are two Star Specs up front w/ 8 months (maybe 6k miles and 10 autocrosses) and two T1R's in the rear w/ 12 months (maybe 8k miles, a track event and 14 autocrosses).

Looking at the fronts, they are both clearly more worn on the inside from the camber, but also worn on the outside edge from hard cornering... and a little "thick" in the middle because I ran 2-3 autocrosses with them underinflated. (I was just too damned lazy to check them... they got down to about 32 psi when they needed to be at least 38) The inside of the RF is table-top smooth, obviously I've been spinning that inside front tire a little too much accelerating out of turns. Shame on me, I should know better! But, looking at the left tire, I think if I'd kept them properly inflated, and had a matching set of 4 to rotate properly front/rear and side/side... the Star Specs would have easily lasted a year and at least 16 autocrosses. (bear in mind that our autocrosses in this area are typically 6-8 runs, not the 3-4 runs that are the norm for some parts of the country)

The rears tell an interesting story, too. They're ragged on the outside from hard cornering, but hardly worn on the inside at all. A VERY clear indication that I could use more negative camber in the rear. The left rear is slightly more worn than the right. No good reason for that other than maybe more autox courses that have hard rights and/or I corner harder to the right than to the left.

What's the plan? Well, I still have that third T1-R that's almost full tread (it only saw a few months of use on the rear of the car), and I can't bear to just pitch it. So I bought a single T1-R to go with it, and that pair will go in the front... the new one on the RF since it sees the most abuse.

On the rear, I'm going to have the other two T1-R's reverse-mounted to put the usable tread on the outside where it is needed. This setup should get me by for at least another 8-10 months.

I'm also going to address the rear camber issue with some shims. I figure about a half degree more negative should help even out that tire wear. BUT, it's going to have the side effect of giving the rear more grip (which is essentially taking grip AWAY from the front, which is bad). So, to counteract that, I'm going to experiment with raising my rear spring rates from 4kg to 7kg. I tried the 7's when I first put the K-Sport kit on the car last April, but at the time, they felt (freakin' great, but) like "too much" because I wasn't used to the car, and I was about to head on a cross-country trip driving on a bunch of race tracks that I'd never been on before... scary! So, I went with a set of 4kg springs instead. Now, I'm much more comfortable with the car, and I'm pretty confident that I have enough adustability with the shock damping and rear tire pressures to tame the rear if necessary.

Hopefully, these changes will all balance with the "not as good as the Star Spec" nature of the T1R's that I'm putting in the front and give me something that I can tolerate on an autocross course.

I'm breaking one of the fundamental rules of suspension tuning by changing more than one thing at a time... tires, rear alignment and rear spring rate. But, I've been doing this long enough that I think I can handle it. (and fine-tuning of this major round of changes WILL be done more methodically) Don't try this at home, folks!

Photos of tires attached. Not for the squeamish. Tires WERE harmed in the making of this post.
Attached Files
File Type: pdf Tires_May2009.pdf (154.5 KB, 51 views)
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Old 05-24-2009, 02:40 AM   #2
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Do you think reverse mounting will affect handling since the tires are directional or is that part of the experience? I've done it before (per a mounting mistake) and only noticed more tire noise. It was the first time I used the tire (older Dunlop from 2002 kinda like the Star Specs) so I actually noticed the noise reduction after the fact.

If I had done it intentionally I would have paid more attention to handling when they were reversed. Reversed tread and handling has been one of those questions in the back of my mind ever since. Let me know how it goes because it could be a real money/tire saver.
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Old 05-24-2009, 10:07 AM   #3
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There are directional tires and there are asymmetrical tires, and a rare few that are both.

Directional tires (like the T1R) have a directional tread pattern that is designed to help evacuate water. You can run them "backwards", they just won't evacuate water like they're supposed to... otherwise they'll work just fine. These tires are usually marked with an arrow showing correct direction of rotation, or sometimes with "right and left" marked on the tire to show which side goes where.

Asymmetrical tires have different tread patterns and sometimes different rubber compounds on each side of the tire, one side of the tire is designed to ALWAYS be on the outside. The tread pattern can run in either direction, the tire just has to be mounted correctly on the wheel. These tires are usually marked with an "outside" marking to show which way to mount them.

The rare few (used to be Corvette tires, don't know if there are any now) that are asymmetrical AND directional require different tires for the left and right side of the car! Glad I don't have to deal with that.

Mounting an asymmetrical tire backwards can have adverse effects because the whole design of the tire is made to work with one side to the outside to take the extra cornering load. Mounting directional tires backwards only affects their wet performance.

In my case, I'm flipping my direction tires on the wheels, but also mounting them on the opposite sides of the car. Net result: They'll still be run in the proper direction.
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Old 05-24-2009, 12:08 PM   #4
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more rear camber (meaning more negative) plus the new springs to counteract that, you will be rock 'n roll. Can't wait to hear your next Auto X report...
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Old 05-24-2009, 12:36 PM   #5
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hankook RS2 or RS3 is my recommendation
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I hate people like you (xbgod) because your the reason I don't come to this board. You spout nonsense and lies and people who don't know any better hold you in high regards because they can't tell the wheat from the chaff.
you nailed it sir.
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Old 05-24-2009, 12:37 PM   #6
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Quote:
Originally Posted by aeipee13 View Post
Do you think reverse mounting will affect handling since the tires are directional or is that part of the experience? I've done it before (per a mounting mistake) and only noticed more tire noise. It was the first time I used the tire (older Dunlop from 2002 kinda like the Star Specs) so I actually noticed the noise reduction after the fact.

If I had done it intentionally I would have paid more attention to handling when they were reversed. Reversed tread and handling has been one of those questions in the back of my mind ever since. Let me know how it goes because it could be a real money/tire saver.
spend a radial compound backwards and you won't like the results.
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Quote:
Originally Posted by xnamerxx
I hate people like you (xbgod) because your the reason I don't come to this board. You spout nonsense and lies and people who don't know any better hold you in high regards because they can't tell the wheat from the chaff.
you nailed it sir.
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Old 05-24-2009, 02:32 PM   #7
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Originally Posted by Tamago View Post
hankook RS2 or RS3 is my recommendation
I I wasn't trying to use up the three T1R's that I have, Hankook's would not be the answer. The hottest street tires on the market right now are the Kumho XS and Toyo R1R. For the price, I'd be going with the Kumho XS.
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Old 05-24-2009, 06:40 PM   #8
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Quote:
Originally Posted by Loren View Post
I I wasn't trying to use up the three T1R's that I have, Hankook's would not be the answer. The hottest street tires on the market right now are the Kumho XS and Toyo R1R. For the price, I'd be going with the Kumho XS.
how does the price of the R1R compare to the RS3? and have you ever run RS2's ? best street tire i've ever run.. besides a toyo RA1
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Quote:
Originally Posted by xnamerxx
I hate people like you (xbgod) because your the reason I don't come to this board. You spout nonsense and lies and people who don't know any better hold you in high regards because they can't tell the wheat from the chaff.
you nailed it sir.
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Old 05-24-2009, 06:53 PM   #9
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R1R's are pricey. $120ish for a 15" size.

You need to get out more, bro. RS2's are decent, I've run them before. They are just a touch below the Azenis 615 in grip and responsiveness, maybe a little better in the rain and in their longevity. But, for competition, the Azenis is clearly the better choice of those two.

But, in the past 2 years or so, a new generation of better street tires has come out.

On the list of "way better than Hankook RS2 or Azenis" is:
Bridgestone Potenza RE01 (recently replaced by the RE11, which is even better)
Dunlop Direzza Z1 Star Spec
Toyo R1R
Kumho XS

The new Kumho is fairly cheap, around $80 for a 15". I've driven on the RE01 and the Star Spec, both were really good... but the R1R and the Kumho XS are in a different league. They offer almost R-tire grip.
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Old 05-24-2009, 07:50 PM   #10
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but can i get a 225 45 15? 225 50 15?

no?
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Quote:
Originally Posted by xnamerxx
I hate people like you (xbgod) because your the reason I don't come to this board. You spout nonsense and lies and people who don't know any better hold you in high regards because they can't tell the wheat from the chaff.
you nailed it sir.
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Old 05-24-2009, 07:51 PM   #11
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But, for competition, the Azenis is clearly the better choice of those two.
i don't believe in street tires for competition, so for the $$ and in the size i want, the hankook is a better choice for me :)
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Quote:
Originally Posted by xnamerxx
I hate people like you (xbgod) because your the reason I don't come to this board. You spout nonsense and lies and people who don't know any better hold you in high regards because they can't tell the wheat from the chaff.
you nailed it sir.
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Old 05-24-2009, 09:01 PM   #12
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Idunno what sizes are available, what do I look like, a tire catalog?

If you're using the tires for purely street use, I have no complaints with the RS2. Excellent street tires.
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Old 06-12-2009, 10:14 PM   #13
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Just to give this thread some closure... here are the results from last Sunday's autocross:
http://fscbmwcca.org/results09.html

2007 Toyota Yaris - $11k
K-Sport coilover kit - $900
Toyo T1R tires - $400

Whooping up on a bunch of BMW's - Priceless
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Old 06-13-2009, 09:28 AM   #14
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