Track tyre wear question

[mitch_f1]

So I have recently noticed that my 205/50/15 R888 tyres are wearing excessively on the outside of the tyre to the point that there is no longer any tyre markings on the outside. Unsure if it differs front to rear because I swap them between trackdays. But on the inside of the tyre it isn't nearly as worn. I have been told that I am not running enough camber because the centre of my tyre is wearing (this was told by the Toyo tech), but alas I am running stock (old) bushes and have got the maximum camber from them (-1.5* front -1.3* rear). At the track I run hot pressures of 32-33psi.

So my question, is this wear pattern due to alignment or tyre pressure or other?

Thanks

Outside edge:


Inside edge:


What I've been told is due to insufficient camber

[Magpie]

Too much positive camber. What are your alignment settings and hot cold pressures?

If the inside worn too much negative. In the middle tyre pressure too high if both sides of the centre too little tyre pressure. Generally speaking.

[mitch_f1]

As above, camber is at -1.5* front -1.3* rear. Hot pressures generally 32-33 psi, cold generally 28.

But yes, that is what I thought. But I cannot get any more negative camber out of the front. Rear I can, but that would upset the balance. In regards to tyre pressure, I wouldn't want to go any lower than 32????

[tbro]

I'm no expert but
Try running toe out and this will help the car will turn in better and hopefully slow down the tread scrubbing.
If your running adjustable shocks as in coilovers, you could try lowering your ride height as this will also increase your neg camber, but you'll need to reset alignment.
If your running std type suspension, maybe try something different other than 888's as they perfer big neg camber to work and wear properly eg 3.5 f 3.0 r 1.5mm out.

Tyre pressures, I start at 25psi@ LS, 26 @ QR, 25 @ EC so depends on the track but you want to aim for 29 to 30 hot, anything higher they get
a bit squimish and not very inspiring. Get a good tyre gauge and check after the first run and adjust from there.

As I said ^^^^ (these are track day pressures not race pressures TD 5 laps, RD 7+laps)

Terry

[Magpie]

Sacrifice caster for camber? As suggested by tbro.

[mitch_f1]

Will try lowering ride height, see if that helps. But with the 205 tyres I find that I get some nasty scrub. But then is it even worth running 205 tyres on a car with stock power, but many suspension and brake mods, should I consider going to 195 on 7 inch rims?

Currently toe is set at 1.5mm out at front, 0.3 out rear

The track days I go to I generally get about 9 laps or so in at a track like wakefield. So with longer sessions do you want a higher pressure, cause I assume the longer the session the hotter the tyres the higher the pressures?

[manga_blue]

R888s always scallop out in that area. It looks a bit weird to someone who hasn't seen it before but that's what R888s do. It's something to do with the way the blocks flex under hgh loads.

Nevertheless you might be better off with more neg camber but it's not really that bad as it is. Lowering it a bit might get you enough increase. Otherwise the alignment looks pretty good.

R888s are usually grippier at 29-31 hot. They get a bit slimy above that. I start them at 24 cold.

[Trackphotos]

Looks like just not enough camber to me. I'm facing the same problem, can't get more than 1.5deg camber at the front and they definitely wear the outside edges too much. All you can do is overinflate them or drive gently :p I'm not certain that kind of wear is unexpected though, everybody seems to suffer similar wear, just maybe over a longer period of time.

More camber can be gotten by lowering the car more at the cost of scrubbing, extending the lower arms/shortening the upper arms, or installing offset bushes. I hear there are track-only adjustable front arms in the works from automotive plus, but they're not ready yet. Magpie has the offset bushes and has I think 3deg camber at the front if I'm remembering correctly.

[manga_blue]

Looks like just not enough camber to me.

The bit I'm looking at is different from normal camber wear. R888s get this little valley about 40mm wide and 2 or 3mm deep developing just outside the centreline of the tyre and heading out towards the outside shoulder. I've had 3 sets and they've all done it. R888s last longer and stay faster if you get them flipped once or twice during the life of the tyre.

[mitch_f1]

If it's dry I will swap left to right, I figure it's cheaper than getting them swapped and that way I can alternate front to rear and left to right between trackdays

[Magpie]

Yep I have offset bushes that allows 3 deg plus of neg camber as well as 7 deg plus of caster. This also could be because I have swapped the lower control arms out as well for new ones. I'm also running 205 tires with +36 offset rims. If your tyres are scrubbing is it on the guards or the liner? If liner then your shocks are not the correct length.

I agree with the comments on the R888's as when I had them on they were sensitive to pressure and did not like going above 32 hot. For that matter neither do the FZ201's, however the R888's would let go with no warning whereas the FZ201's still give feedback when getting too much pressure in them.

I would say that that is too much toe on the front and will cause excessive wear very quickly. You could go toe out on the front and toe in on the rear.

[Dan]

If it's dry I will swap left to right, I figure it's cheaper than getting them swapped and that way I can alternate front to rear and left to right between trackdays

Flipping will save you money since you'll get more track days out of the tyres.

Just rotating them means that the outside side of the tyre is still the same, flipping will change the inside which isn't being worn with the outside so you can use up the whole tyre.

Then after you flip continue to rotate to even out the wear between them.

[MattR]

I'm no expert but
Try running toe out and this will help the car will turn in better and hopefully slow down the tread scrubbing.
If your running adjustable shocks as in coilovers, you could try lowering your ride height as this will also increase your neg camber, but you'll need to reset alignment.
If your running std type suspension, maybe try something different other than 888's as they perfer big neg camber to work and wear properly eg 3.5 f 3.0 r 1.5mm out.

Tyre pressures, I start at 25psi@ LS, 26 @ QR, 25 @ EC so depends on the track but you want to aim for 29 to 30 hot, anything higher they get
a bit squimish and not very inspiring. Get a good tyre gauge and check after the first run and adjust from there.

As I said ^^^^ (these are track day pressures not race pressures TD 5 laps, RD 7+laps)

Terry

What Terry said.

Being a car that sees road and track use the setup by necessity is a compromise, so the tack tyres will suffer.

The 888's seem to wear like that on road spec alignments. 3.5degrees of neg camber isn't fun on the road for normal tyre wear. Be thankqful you're trying to get 6deg of neg camber to suit some slick tyres, like the yokahama slicks i used to run that came off the old supertourers.

Best suggestions is to strip and refit tyres to extend the life a bit, but with r spec semis on a road car you will always be compromised for tyre wear and performance, but you will get that type of tyre wear.

And get a hot pressure of 30psi measured as quickly as you can, i.e. jump out of car and measure before you do anything else when you pull up.

[Scoota]

The obvious answer to your outside edge wear is more negative camber. I have a similar issue: 2.4 degrees is not quite enough for me, but it's as much as I can get. Regarding the band of wear, I have suffered from a similar wear pattern with my last two sets of R888's, but I recently resolved the issue by increasing my tyre pressures. The odd wear pattern is caused by the tyre deforming under lateral load. This is rectified by running more pressure. The scenario was as follows...

Phillip Island GP Circuit, 10 deg day (fkn cold!). I was setting my cold pressures to 28psi, which would give me a hot pressure of around 32psi. This was resulting in the wear pattern shown in your photo - not ideal. A very knowledgeable fellow examined my tyres and suggested that I increase my cold pressures, so I did, setting them to 30psi cold. On this particular day I was having no problem with the tyre "going off" (temp too high), and when I checked the hot pressures they were around 33.5psi. The resultant wear pattern was brilliant, as per the picture. This indicated that the tyre deformation issue was not occurring - happy days!

A word on "hot pressures"... On cool days, your tyres will cool very rapidly on your "in lap", causing tyre pressure to decrease in response. Checking your hot pressures gives you some useful data, but setting your cold pressures before going out onto the track is more important. It gives you a known starting point for every session. Track conditions, weather conditions and your driving style will then dictate how much temp and pressure you pick up during the session. Ultimately you are trying to achieve the optimum hot tread temperature to maximise grip. Your starting cold pressure is one of the variables that effects that outcome.

Closing comments...

1. This was my first success with running higher cold tyre pressures, and I am very pleased with the results. It's the first time I have got even wear across tyre, even after having focussed very strongly on camber settings to get even temperature distribution across the tyre (less than 10 deg C difference across the tyre). So, despite achieving reasonably good camber settings for my car (which unfortunately you can't achieve), I was never able to resolve the tread distortion and uneven wear.... Until I tried running a bit more pressure. Problem solved.

2. Why was I running 32psi hot? Because that is what most others run. Perhaps the majority aren't right on this occasion.

Try it yourself. Hopefully you get good results, like I did. I am doing a sprint meeting this weekend. If I get vastly different results this weekend I will let you know.

Cheers.
Ps. I was able to pull 1.8 seconds out of my personal best, registering a 2:01.3 at Phillip Island, so I was stoked!! This was achieved in my last session of the day, so I am fairly certain that the tyre pressure alteration was a contributing factor.

[greasemeup]

Curious if motorcycle wear patterns are from the same conditions as car patterns?
I can't see why not.

There are some excellent videos by Dave Moss on u tube that may be useful.


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