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[BGR]

I'll be doing my first track day on a brand new set of ZIIs this Saturday. Weather looks to have a high in the mid 60s and overcast skies. On a stock M-Sport suspension, is there a good starting cold tire pressure? I was thinking starting at 36 all around (225 front/255 rear) unless there are other suggestions.

[dcaron9999]

I just installed a 255/35R18 square set of brand new ZII's on my 135i this week, and did one lapping session with them so far.

The stiffer sidewall tires felt really nice and precise on the track (better than my previous set of RE-11's), but were a bit slippery because of the cold weather, slight drizzle, and new tires needing mold release lubricant to wear off...

I started with 32 PSI warm pressure, and hot pressure reached 38PSI. I took some measurement with a laser pyrometer, and noticed the middle of the tire getting hotter, which means pressure was too high. Will keep monitoring and adjusting tire pressure on next lapping events, until I find a sweet spot.

Also getting a new alignment done tomorrow.

[BGR]

Originally Posted by dcaron9999

I just installed a 255/35R18 square set of brand new ZII's on my 135i this week, and did one lapping session with them so far.

The stiffer sidewall tires felt really nice and precise on the track (better than my previous set of RE-11's), but were a bit slippery because of the cold weather, slight drizzle, and new tires needing mold release lubricant to wear off...

I started with 32 PSI warm pressure, and hot pressure reached 38PSI. I took some measurement with a laser pyrometer, and noticed the middle of the tire getting hotter, which means pressure was too high. Will keep monitoring and adjusting tire pressure on next lapping events, until I find a sweet spot.

Also getting a new alignment done tomorrow.

So you are recommending starting lower, around 32 PSI?

[02rsxpilot]

I run ZIIs on stock M-Sport suspension in the same sizes. I typically start the day dropping the pressures a couple pounds from the factory specs, so 34 front, 37 rear. As the day warms up, I'll usually drop them another pound or two. If it starts to cool again, like in the winter, I start adding pressure back in for the last session or two.

The main thing to pay attention to for your pressures is your sidewall rollover. The ZIIs have a nice little arrow on the sidewall. You don't want your wear to move past the tip of that arrow. If you do, add pressure. If you aren't to the arrow, lower pressure. Also remember that changing 1 psi cold is more than 1 psi hot, so your adjustments will vary based on when you do them (first thing in the morning, or right after a session). Since us stock suspension guys can only get about .5 degrees of camber, we can't drop the pressures as much as might be ideal without rolling over too much.

dcaron, your camber settings are a long way away from stock m-sport, and laser pyrometers are unreliable at best. I wouldn't use the data from that personally, because even if you come right off a flying lap into the hot pits to measure, the surface temp of the tires will already have cooled and cooled unevenly (the outer tread gets more air and cools faster). You're readings will also be highly impacted by whatever kind of corners lead up to the hot pits. A needle-pyrometer is a much better way to go, although still hard to get true tire temps from due to cooling. My two cents...

[BGR]

Originally Posted by 02rsxpilot

I run ZIIs on stock M-Sport suspension in the same sizes. I typically start the day dropping the pressures a couple pounds from the factory specs, so 34 front, 37 rear. As the day warms up, I'll usually drop them another pound or two. If it starts to cool again, like in the winter, I start adding pressure back in for the last session or two.

The main thing to pay attention to for your pressures is your sidewall rollover. The ZIIs have a nice little arrow on the sidewall. You don't want your wear to move past the tip of that arrow. If you do, add pressure. If you aren't to the arrow, lower pressure. Also remember that changing 1 psi cold is more than 1 psi hot, so your adjustments will vary based on when you do them (first thing in the morning, or right after a session). Since us stock suspension guys can only get about .5 degrees of camber, we can't drop the pressures as much as might be ideal without rolling over too much.

dcaron, your camber settings are a long way away from stock m-sport, and laser pyrometers are unreliable at best. I wouldn't use the data from that personally, because even if you come right off a flying lap into the hot pits to measure, the surface temp of the tires will already have cooled and cooled unevenly (the outer tread gets more air and cools faster). You're readings will also be highly impacted by whatever kind of corners lead up to the hot pits. A needle-pyrometer is a much better way to go, although still hard to get true tire temps from due to cooling. My two cents...

Great info, thanks.

I've been racing sportbikes in middleweight/lightweight for the last 5 years and am now just starting to get into cars. I am actually somewhat surprised that the price per tire is relatively constant bike vs car. You just need four for a car...

[MightyMouseTech]

Surface temps are pretty much meaningless, unless they are real time. You need a probe that gets close to the core rubber like rsxpilot said.

I use a Longacre similar to this:



I have found the ZII's like to run about 40 PSI when hot. So, set them to about 32-34 cold, go out and do about 4-5 laps at speed, come in and bleed them down to 40. Later on you can let your tires fully cool down and you will know your starting cold pressure. Usually it is a different pressure for every tire, and will be different for every track.

You can adjust that for conditions like the tire rolling over the edge and uneven temperatures, but that is a bandaid solution to poor suspension set up.

[02rsxpilot]

Originally Posted by MightyMouseTech

Surface temps are pretty much meaningless, unless they are real time. You need a probe that gets close to the core rubber like rsxpilot said.

I use a Longacre similar to this:

Exactly what I use as well. Was like $100 on Amazon.

[dcaron9999]

Originally Posted by 02rsxpilot

dcaron, your camber settings are a long way away from stock m-sport, and laser pyrometers are unreliable at best. I wouldn't use the data from that personally, because even if you come right off a flying lap into the hot pits to measure, the surface temp of the tires will already have cooled and cooled unevenly (the outer tread gets more air and cools faster). You're readings will also be highly impacted by whatever kind of corners lead up to the hot pits. A needle-pyrometer is a much better way to go, although still hard to get true tire temps from due to cooling. My two cents...

My latest alignment specs are: -2.8* camber in the Front, and -1.8* in the rear. Toe is 0 in the front, and 0.21* toe in on each side in the rear.

Did not want to pay that much for a needle pyrometer (paid $30 for my laser pyro). I want an approximate temperature delta across the tread as sson as I come into the pits, for a general idea of my under/over inflation, and camber and toe adjustment impacts. I realize that this is far from the optimal method but still a valid indication ...

[dcaron9999]

Originally Posted by MightyMouseTech

Surface temps are pretty much meaningless, unless they are real time. You need a probe that gets close to the core rubber like rsxpilot said.

I have found the ZII's like to run about 40 PSI when hot. So, set them to about 32-34 cold, go out and do about 4-5 laps at speed, come in and bleed them down to 40. Later on you can let your tires fully cool down and you will know your starting cold pressure. Usually it is a different pressure for every tire, and will be different for every track.

That is more or less my approach on purging pressure as well. If I do up to two 20-minute sessions/hour, I usually aim/purge down to mid-thirty PSI hot pressure, as soon as I come into the pits. At one point during the day, hot pressure stabilizes, and adjustments are no longer needed ...

[MightyMouseTech]

Originally Posted by dcaron9999

Did not want to pay that much for a needle pyrometer (paid $30 for my laser pyro). I want an approximate temperature delta across the tread as sson as I come into the pits, for a general idea of my under/over inflation, and camber and toe adjustment impacts. I realize that this is far from the optimal method but still a valid indication ...

Surface temps will even change as you go through a corner, let alone drive down pit lane, stop, get out, and measure the temps.

[dcaron9999]

Originally Posted by MightyMouseTech

Surface temps will even change as you go through a corner, let alone drive down pit lane, stop, get out, and measure the temps.

Even if the temps do change, tires will still hold some heat, which should provide a pattern (area of the tire doing most work or under most strain), correct?

[timbo_3101]

Originally Posted by dcaron9999

Even if the temps do change, tires will still and hold some heat, which should provide a pattern (area of the tire doing most work or under most strain), correct?

dcaron, your overall (scientific) approach is to be commended. Sharing data and experience is extremely generous given the paucity available online. Some data is better than no data ie those attending track events "just for fun" are forgoing an opportunity for improvement.

Once you are comfortable with a standardised measuring technique and evaluation, you can correlate temperatures with treadware. At best, this will provide you with an early indication of alignment or tyre inflation. At worst, you have lost nothing.

Your escalation in efforts will ultimately be rewarded - probably after several events - in technical expertise, in operating costs, in confidence yourself, and in respect from competitors

(In fact, my initial concern three months ago was how you had worn the outside shoulders of RE-11 with approximately -3o camber. Unless you had an aggressive set up and extremely aggressive driving style, I would have thought this to be impossible.)

[dcaron9999]

Originally Posted by timbo_3101

dcaron, your overall (scientific) approach is to be commended. Sharing data and experience is extremely generous given the paucity available online. Some data is better than no data ie those attending track events "just for fun" are forgoing an opportunity for improvement.

Thanks but in all honesty, I picked up from the expertise level on this forum and others willing to share their experience. It is what lead me to do the same, and inquire. Im not even close to some of the talented enthusiasts on here ...

Originally Posted by timbo_3101

Once you are comfortable with a standardised measuring technique and evaluation, you can correlate temperatures with treadware. At best, this will provide you with an early indication of alignment or tyre inflation. At worst, you have lost nothing.
Your escalation in efforts will ultimately be rewarded - probably after several events - in technical expertise, in operating costs, in confidence yourself, and in respect from competitors

That is the goal. Just trying to find optimal settings with limited amount of resources, as this hobby can get quite expensive, and I want to spend the money where there is greatest return.

Originally Posted by timbo_3101

(In fact, my initial concern three months ago was how you had worn the outside shoulders of RE-11 with approximately -3o camber. Unless you had an aggressive set up and extremely aggressive driving style, I would have thought this to be impossible.)

All part of the learning experience. At first, when I I bought my 2011 135i last summer, I bought 225/40R18 front tires & 255/35R18 rear RE-11 tires, and started lapping with stock camber.

After a short while, I noticed the accelerated wear on the outer edges of the front tires, and went for the first mod (breaking the strut tower alignment pins to gain minor negative camber). Did a bit of lapping, realized this modification was not enough, as my car still understeered and chewed up the exterior of my front tires.

I ordered camber plates and front M3 control arms, and dialed up as much max negative camber as possible (about -3.2*). I finally equalized the wear pattern and reduced the understeer considerably. All of this time, I did my weekly lapping on a cement pavement (airport track) 10 minutes from where I live.

Fast forward to this season (April 2014). Just got a Quaife LSD installed. I booked a 2.5 days intensive driver education event, (on an asphalt track), with my now worn RE-11 tires (at wear bars in the rear, and no tread left in the front). We did about 8 20-minutes session/day. I monitored and adjusted hot tire pressure to 34PSI, and was amazed at the good grip I was getting (asphalt and cement pavement are so different). My 135i felt neutral, with mild oversteer at turn out. The worn RE-11 were now acting like slicks. This was the best handling I had experienced with my 135i.

I was now due for new tires, and decided to go wider in the front with a used rear set of stock RIMS ( style 261 18x8.5 ET52) + 10mm spacer thazt I got for very little money. I bought a 255/35R18 Dunlop Direzza ZII tire square setup and did one session at the local ICAR track (cement track). I loved the accuracy and communication of the ZII tires, probably due to the stiffer sidewall over the RE11's. Having said that, I found the brand new ZII tires to be a bit slippery and they squealed at the limit. Got to give them a chance to break in I suppose.

Im not done yet with selecting ideal hot pressure, camber and toe settings, for optimal dual-duty wear and grip - this is "work in progress" as I adapt to the stiffer ZII's and 255/35R18 square setup.

[BGR]

Is this considered wear past the triangle?

[Kgolf31]

The triangle is just is a starting point. You can wear past the triangle and it is perfectly fine.

My wear is about half way down the triangle on the front, and at the top of the tip in the rear. It is all dependent on how you like the feel of the car at a certain pressure

[BGR]

Originally Posted by Kgolf31

The triangle is just is a starting point. You can wear past the triangle and it is perfectly fine.

My wear is about half way down the triangle on the front, and at the top of the tip in the rear. It is all dependent on how you like the feel of the car at a certain pressure

It feels like I'm rolling over the tire a little. Might just be the suspension, but I'll try adding some pressure.

[02rsxpilot]

That looks spot on to me BGR. Kgolf is right, you can go a bit further, and a couple of mine have ended up about half way down the triangle, but if you are right there at the tip it gives you some margin for error.

[Suprgnat]

Originally Posted by BGR

Is this considered wear past the triangle?

AFAIK, the triangle is just telling you where to look for the tire wear indicator in the tread. My PSSs have little, tiny Michelin men at each location on the sidewall and some tires just have TWI embossed on the sidewall.

[Kgolf31]

Originally Posted by BGR

It feels like I'm rolling over the tire a little. Might just be the suspension, but I'll try adding some pressure.

Mark it with chalk. It will tell you exactly where you're rolling over.

[Kgolf31]

Originally Posted by Suprgnat

AFAIK, the triangle is just telling you where to look for the tire wear indicator in the tread. My PSSs have little, tiny Michelin men at each location on the sidewall and some tires just have TWI embossed on the sidewall.

No, it is an indicator of where you should be rolling over your tires.

[Suprgnat]

Originally Posted by Kgolf31

No, it is an indicator of where you should be rolling over your tires.

"On MICHELIN tires, you can find the location of the wear bar indicators around the tire by looking for a small Michelin Man at the edge of the tread."

http://www.michelinman.com/tires-101...nd-damage.page

[Kgolf31]

Originally Posted by Suprgnat

"On MICHELIN tires, you can find the location of the wear bar indicators around the tire by looking for a small Michelin Man at the edge of the tread."

http://www.michelinman.com/tires-101...nd-damage.page

No surprise...PSS tires aren't performance tires like Dunlop, Hankook, and BFGs