Jump to content

Tire temps vs Tire wear advice?


CBraden
 Share

Recommended Posts

Seeing if there is wisdom out there that anyone cares to share.

 

Tire temps (one sample - this was with our driver that is least hard on the tires which we think accounts for the huge middle to outer delta):

Inner     Middle   Outer

164       157          143  <<<RF

161        156          134  <<<RR

 

Tire wear (tread depth after two day race):

6mm inner,  7mm middle,  4mm outer  <<<RF day2, was RR day1

 

These two indicators seem to be telling the opposite story about the setup...  Temps say to reduce camber  (to even out temps), Wear says to increase camber (to even out the wear).

 

The car handles well, no complaints there. It also stops pretty well, but we suspect it would stop better with less static camber - still no complaints. Toe was 1/16"i n, we will likely go 1//16" out next race, don't know how that will impact wear on inside tire, but don't expect it to make a big difference.

 

What would you do with pressure and camber?


 

 

 

 

Link to comment
Share on other sites

Tire temps seem high across the board.  We don't like the tire temps to get higher than 150 at any point in the tire.

 

I think you are sliding the tires.

 

Also, how soon was the temp taken?  This looks like the outside had time to cool and wasn't beat on right before temps were taken.

 

I am guessing here.....  I think you have too much temp in general.

 

I only have 3 cars of data to go by.  I may be way off base.

 

What's your hot pressures?  We start at 26 and end up at 34 hot all around with 225 45 15 rs4.

  • Thanks 1
Link to comment
Share on other sites

The max grip will come with the outer edges about 15* cooler than the center. (Chump Radials, R7, DOT R tires,)   This allows the edge to cool and not grease up or overheat.  .  It also shows a better footprint.  

 Front;  If you boost pressure a little maybe 3#. the wear will even out , but the outer edge wil drop a couple . Maybe  add 2# pressure and  reduce camber .5*    For wear.   Looks pretty good for grip as is. 

 

 Rear  needs .5 less camber /more pressure. .   It is over the  optimal 15* spread.  

  More Pressure acts like camber , keeping the outer edge cooler .   It is really hard to get the centers too hot. 

 For Chump, have the outer edges cool works better/ longer.   Chump fronts like about 1.5-2 dynamic camber(working)  That can be 1* on a Vette or 3 on a strut front car.   IE my Chump Miatas run at 2 static , the VW at 3 DS, 2.0 PS, , and the super truck @ 2.5. DS, 2.0 PS.  

 If the car is good and tires last the entire race. leave it. IMHO. 

 

  Toe; camber scrub is reduced by toe out ,but for some reason the Chumpers eat inner edges with much toe out , I  think the inner edges get hot and simply stay hot . So  I set all of mine to zero front and a wee bit out rear. 2MM.  If the  worst driver cant go straight, reduce the rear toe out. Miata/ VW . 

  • Thanks 1
Link to comment
Share on other sites

  • Members
14 hours ago, CBraden said:

Seeing if there is wisdom out there that anyone cares to share.

 

Tire temps (one sample - this was with our driver that is least hard on the tires which we think accounts for the huge middle to outer delta):

Inner     Middle   Outer

164       157          143  <<<RF

161        156          134  <<<RR

 

Tire wear (tread depth after two day race):

6mm inner,  7mm middle,  4mm outer  <<<RF day2, was RR day1

 

These two indicators seem to be telling the opposite story about the setup...  Temps say to reduce camber  (to even out temps), Wear says to increase camber (to even out the wear).

 

The car handles well, no complaints there. It also stops pretty well, but we suspect it would stop better with less static camber - still no complaints. Toe was 1/16"i n, we will likely go 1//16" out next race, don't know how that will impact wear on inside tire, but don't expect it to make a big difference.

 

What would you do with pressure and camber?


 

 

 

 

Tire wear makes sense to me. You should want about a 10-15 degree difference across and then we have even tire usage long term. So 164 - 153 - 144. Middle seems a bit high, maybe 1-2 psi. Based on inside and outside camber seems close. I also think when you come down in pressure the middle will lessen and outer will increase the middle is not doing as much of the work.

RR is way worse and might be 2-3 psi high and should be 161-149-134.

RF camber seems good. RR might need .2-.4ish degrees less.

 

We went from 1-2 races on a set of tires to 2-3 on the same tires same tracks when we got the tire temps just right and even.

  • Thanks 1
Link to comment
Share on other sites

I was away with work and garage work all day yesterday, so just getting back to this. This is really good feedback and I am studying it. Looks like I need some testing days to play with different alignment and pressure settings (and try the recommendations above).

 

I will try to address the questions posted above here:

* Temps were taken as soon as the car stopped on pit row  (not a long pit road)

* There is usually some sliding going on, but not huge slip angles, just moving it around a bit (car will rotate @ driver discretion)

* Not been worried about temps if tires don't 'go off'... (and these weren't getting greasy at any point in race - no idea how much headroom if any on temps to that point)

* Track was Hallett OK, CCW

* Car is strut front, -3.5* camber

 

I really appreciate the feedback, and am learning from it. Great community willing to share their experience like this...

Link to comment
Share on other sites

2 hours ago, MR2 Biohazard said:

Tire wear makes sense to me. You should want about a 10-15 degree difference across and then we have even tire usage long term. So 164 - 153 - 144. Middle seems a bit high, maybe 1-2 psi. Based on inside and outside camber seems close. I also think when you come down in pressure the middle will lessen and outer will increase the middle is not doing as much of the work.

RR is way worse and might be 2-3 psi high and should be 161-149-134.

RF camber seems good. RR might need .2-.4ish degrees less.

 

We went from 1-2 races on a set of tires to 2-3 on the same tires same tracks when we got the tire temps just right and even.

 

You didn't find that the tires heat cycled out after the first 2-3 days of racing? What tires if you don't mind me asking. We noticed on Day 2 in the last couple of stints the RS4's at this race were moving around significantly more at the same lap times, which we assumed was the tires starting to heat cycle out...

 

 

Link to comment
Share on other sites

  • Members
12 hours ago, CBraden said:

 

You didn't find that the tires heat cycled out after the first 2-3 days of racing? What tires if you don't mind me asking. We noticed on Day 2 in the last couple of stints the RS4's at this race were moving around significantly more at the same lap times, which we assumed was the tires starting to heat cycle out...

 

 

They do heat cycle out at the end, but that is OK for me. They are like 2 seconds a lap slower, but it happens gradual. The only bad thing that I did once was ruined some and put on a new pair and used and old pair. I used the new on the front and old on the rear. That was a bad idea. Car was crazy oversteer and not stable. If you change them use the new on the rear.

 

Edited

I have used rs3's for a few years and at AMP was the first time on RS4 as we finally ran out of most of our supply of RS3. We still have some that are good for 7-8 hour races we will use.

Edited by MR2 Biohazard
  • Thanks 1
Link to comment
Share on other sites

On 11/10/2017 at 7:45 PM, Bandit said:

Are you using a pyrometer with a probe to get deep into the rubber?

 

More accurate than surface temps.

 

Yes, the temps reported above were taken by a crazy high tech one that not only records them all, but also normalizes pressure to 80* temps if you ask it to. We always use a probe for tire temps.

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...