Boss 302 Advance Road Race Tire setup thread

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

Another thing I heard was to adjust pressure until the tire rolls over onto the indicators. Is there anything to this approach? Or is this superseded by measuring temps with a pyrometer? Turns out that running 35 PSI front and 37 PSI rear [hot measured at the paddock] gets my Nitto NT-01 275F / 305R tires to roll right to the indicators, so this was my target hot pressure for my last event at VIR. Held very steady throughout weekend.

The sidewall indicators (the distance between the indicators and the wear marks are sometimes called "chicken strips" BTW) are another tool to use, and in a perfect world the temps would match across the tire and at the same time the wear would come exactly up to the indicators..but we don't live there often, so IMO the temps would take precedence, but it is another reference, and baring the use of the pyrometers , probably a good one.

I was told to set pressures hot and then I read them cold before the next session to set a baseline for 1st sessions on subsequent days. I always write down the air temp but don't have a way to measure tire temp [yet]. I've noticed as much as 1.5 psi difference just because 1 side of the car was getting sunlight and the other side was in the shade.

Not uncommon, this is why tires are usually covered in the pits with blankets, or left in the shade, however, once the pressures are set (at the right temps) does it really matter if one side is higher than the other? HhMMMMMMMMMMmm chew on that one. ???

Let me ninja-edit and add to this for the sake of discussion, you have a setup on the car, you know that in the last session the pressure was...28 cold when you went out and 41 hot when in,(for simplicity's sake they're all the same) the car is now on the grid. one side is in the shade. The pressure is 28 in the shade and 29.5 in the sun..what do you do about that?

 

[Hermes]

Re: Boss 302 Advance Road Race setup thread

Let me ninja-edit and add to this for the sake of discussion, you have a setup on the car, you know that in the last session the pressure was...28 cold when you went out and 41 hot when in,(for simplicity's sake they're all the same) the car is now on the grid. one side is in the shade. The pressure is 28 in the shade and 29.5 in the sun..what do you do about that?

I would do nothing since they would eventually heat up to the same 41 hot when driving. I also notice that cold pressure will go up during the day as the ambient temperature goes up [makes sense, since your cold is not as cold as it once was]. In the past I would do nothing other than write down the temp for future ref, but I would make any adjustments hot.

Thanks for the info about the roll indicators, I was thinking the same thing [good ref but not as good as temp distribution], but it was good to have you confirm that.

Really looking forward to playing around with camber, tire pressures, and measuring temps next season.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

I would do nothing since they would eventually heat up to the same 41 hot when driving. I also notice that cold pressure will go up during the day as the ambient temperature goes up [makes sense, since your cold is not as cold as it once was]. In the past I would do nothing other than write down the temp for future ref, but I would make any adjustments hot.

Thanks for the info about the roll indicators, I was thinking the same thing [good ref but not as good as temp distribution], but it was good to have you confirm that.

Really looking forward to playing around with camber, tire pressures, and measuring temps next season.

OK, how would you confirm that while sitting on the grid? For the case in point, there is no "hot adjustment" you have to get it right, out of the box.

 

[Hermes]

Re: Boss 302 Advance Road Race setup thread

I see your point, which I think is a BIG difference between racers who have to get it right the first time and DE slackers like me that need at least 1 session to knock the rust off, learn the track etc.

But I really do see your point. I have all my data in a small log book, but if I start to fill it into a spreadsheet, it would be a whole lot more useful. Eventually I could measure cold tire temps [correct? ideally. should I correlate pressure to tire temp, not ambient air temp?]. If I start logging data now, hopefully by the time my driving is good enough to use the data [i.e. get the cold pressure right the first time] I'll have enough data to get me close.

Again thanks for all the input and advice, I find this car set up stuff really interesting.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

Yes pressure should always be related to tire temps,(keeping in mind that sometimes air temp and tire temp are the same) . Now, we are just talking one tire, most likely you will run at least 2 different pressures (front and rear) and sometimes as much as 4 (RF ,LF, RR, LR) depending on the situation. That is a little more advanced, for now...baby steps, create the graph accurately as possible.


FWIW I have the "master intergalactic tire pressure temp interface graph" so you guys will be graded

 

[2012YellowBoss]

Re: Boss 302 Advance Road Race setup thread

Gary - John seems to me that living in S. FL with high humidity and hot track surface is giving me more of a increase in pressure, not driving harder. Maybe Blacksheep can say if he saw this in the CTSCC series even if those guys drive harder then we do. I get any where from 9-11 increase but have seen as much as 13-14 PSI more. Advise from a non-expert but if you are looking for a good starting pressure I would say go around 8 PSI below where you want the hot pressure to be. My thinking here is under inflating the tire can cause more damage and be less safe then a slightly over inflated tire. Like Blacksheep said get the pressure the morning after the track day will be the best way to have good starting point in the future.

FWIW Gary you do not lose too much in the way of pressure if you have to take it in the paddock. Depending on the "cool down" lap I see only 1-2 PSI different then getting the pressure in the hot pits. If I get caught behind someone really slow for the entire last lap I don't really want to count the PSI but if it just a little slower or only slow the last few turns I would say 2 PSI loss at most. If you can run most of the lap hard and then ride into the paddock you will only lose a pound.

My guess is the heat from the brakes help keep the pressure up. However getting tire tread temps can be very different in the paddock vs. the hot pits 15-30 degrees. I have had several occasions to get PSI and temps in the hot pits and this is what I have seen.

 

[Grant 302]

Re: Boss 302 Advance Road Race setup thread

One thing that surprises me is that I don't hear often that people use a lower pressure in the rear tires. For me, the habit developed mostly from the way I run cars on the street. Typically I use 3 to 6 lbs. less in the back. Our cars are in the 20-30% range lighter in the back and I find it better for overall grip and wear to adjust the pressure similarly.

 

[06mach1]

Re: Boss 302 Advance Road Race setup thread

One thing that surprises me is that I don't hear often that people use a lower pressure in the rear tires. For me, the habit developed mostly from the way I run cars on the street. Typically I use 3 to 6 lbs. less in the back. Our cars are in the 20-30% range lighter in the back and I find it better for overall grip and wear to adjust the pressure similarly.

I have been using 1 lb. less in the rear. I have been running hot, 41 up front and 40 in the rear with stock p-zero's.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

So is anyone running this weekend and taking notes?

 

[Jimmy Pribble]

Re: Boss 302 Advance Road Race setup thread

So is anyone running this weekend and taking notes?

I'm pretty sure we need a group buy on these first.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

or one of these if you have a memory like mine

http://www.longacreracing.com/catalog/item.asp?id=188&catid=7

 

[cloud9]

Re: Boss 302 Advance Road Race setup thread

This is a great thread Steve. I'll try to chart some info this weekend with my new R6s. That said, after reading this, I'm really confused on optimal HOT temps. I know the goal is to get the COLD temp right, but at the end of the day it's the HOT temp we're driving on isn't it? I've tried low 30s hot on R6s but have found high 30s to 40 works better for me...probably because our cars are so heavy.

The ambient temps are projected to be in the mid 70s. I'm assuming if I start at 32 front and 31 rear I should end up around 40 HOT. Any suggestions? Also I do have a probe style temp gun, but is it relevant if you run a cool down lap, then drive through the paddock to your trailer? In other words, have the tires cooled too much to get good data?

OMG have I found some pressures and sizes that work on R6s!!!!!

I just put on a set of 315/30/18s and 295/30/18s for the Mustang Roundup last weekend. I started at the following COLD and resulting (HOT) pressures:

LF 32 (43) RF 33 (43)
LR 31 (39) RR 32 (39)

This worked really well and I set a PB lap time by 1.8 seconds! I was a little higher HOT than I wanted to be so I dropped down on Sunday

LF 31 (42) RF 32 (42)
LR 30 (38) RR 31 (38)

This dropped me another 0.8 seconds on a track I have plenty of laps on previously. There's more there, but I had a 302S spin in front of me and then I ran into traffic after that.

The ambient temp was 60F when we started, and ending around 70F later in the morning. I didn't mess with dropping pressures once I hit the HOT temps I was targeting and as blacksheep said they came back up to the same HOT temps. R6s really like more pressure on our heavier cars. It did "feel" a little high, but I did notice how as long as I trusted the grip the car stuck. Hoosier obviously knows what they're talking about with their pressure recommendations.

I tried taking some tire temps but they were useless by the time I got the probe on them as the inside edges were hotter from "rolling" in on the cool down lap and into the paddock with so much camber. I definitely was heating the outside edges more during the competition.

 

[Grant 302]

Re: Boss 302 Advance Road Race setup thread

I tried taking some tire temps but they were useless by the time I got the probe on them as the inside edges were hotter from "rolling" in on the cool down lap and into the paddock with so much camber. I definitely was heating the outside edges more during the competition.

I wouldn't be too sure about that. When running higher pressures, *sometimes* you don't need as much camber for max grip and even wear. When I see higher inside temps, I'm inclined to reduce the camber a little. Usually pictures on track can back that up if you're not anywhere near running into positive camber.

 

[cloud9]

Re: Boss 302 Advance Road Race setup thread

I wouldn't be too sure about that. When running higher pressures, *sometimes* you don't need as much camber for max grip and even wear. When I see higher inside temps, I'm inclined to reduce the camber a little. Usually pictures on track can back that up if you're not anywhere near running into positive camber.

I guess I'm going off tire wear more than anything. The outside edges are wearing faster than the inside.

 

[Grant 302]

Re: Boss 302 Advance Road Race setup thread

I guess I'm going off tire wear more than anything. The outside edges are wearing faster than the inside.

If that's running on the higher pressure with a new tire...I would make adjustments on the visible wear. If it was on tires that started with outside wear and run with lower pressure before, you can almost ignore the wear pattern. Reading tire wear after making major adjustments is more of an art than science!

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

OMG have I found some pressures and sizes that work on R6s!!!!!

I just put on a set of 315/30/18s and 295/30/18s for the Mustang Roundup last weekend. I started at the following COLD and resulting (HOT) pressures:

LF 32 (43) RF 33 (43)
LR 31 (39) RR 32 (39)

This worked really well and I set a PB lap time by 1.8 seconds! I was a little higher HOT than I wanted to be so I dropped down on Sunday

LF 31 (42) RF 32 (42)
LR 30 (38) RR 31 (38)

This dropped me another 0.8 seconds on a track I have plenty of laps on previously. There's more there, but I had a 302S spin in front of me and then I ran into traffic after that.

The ambient temp was 60F when we started, and ending around 70F later in the morning. I didn't mess with dropping pressures once I hit the HOT temps I was targeting and as blacksheep said they came back up to the same HOT temps. R6s really like more pressure on our heavier cars. It did "feel" a little high, but I did notice how as long as I trusted the grip the car stuck. Hoosier obviously knows what they're talking about with their pressure recommendations.

I tried taking some tire temps but they were useless by the time I got the probe on them as the inside edges were hotter from "rolling" in on the cool down lap and into the paddock with so much camber. I definitely was heating the outside edges more during the competition.

Good job, as mentioned a few posts down, were these new or old tires? Also , even if the tires have cooled down still write down the temps as they can still be useful. You are also doing the correct thing by concentrating on HOT pressures and doing what ever you have to in order to get there, by allowing them to cool you now have a decent starting spot....at least at 60 and 70 degrees anyway Feel like sending me the info and I'll try to put them through my crystal ball?
Also don't be afraid to mark up the side of the tires with a piece of chalk to establish your new "wear" pattern, stripe the inside and the outside and see what happens.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

I wouldn't be too sure about that. When running higher pressures, *sometimes* you don't need as much camber for max grip and even wear. When I see higher inside temps, I'm inclined to reduce the camber a little. Usually pictures on track can back that up if you're not anywhere near running into positive camber.

this where the tire temps across the face would really be nice, you would know exactly which way to go.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

TTT...time to get back to work, did anyone do any track days this week?

 

[ArizonaBOSS]

Re: Boss 302 Advance Road Race setup thread

TTT...time to get back to work, did anyone do any track days this week?

I did, but I didn't do my homework

On the other hand, I didn't let out any air between races. Only running 4 sessions a day is much easier than the 6 I used to run when it was 4 + 2 TT. Now the tires come back down to the right pressures before each session/race.

 

[blacksheep-1]

Re: Boss 302 Advance Road Race setup thread

I try to help and this is the help I get..