Tire conundrum

[blacksheep-1]

What are your spring rates, what kind of shocks and what bars are you using, I'm assuming it's a Boss 302..correct?
IMO you can't hardly run enough camber in the front of a mustang.
Let me expound on that, what these guys are saying is true, you need to measure temps across the tread surface, now, take that with a grain of salt, because our tires run..about a 50 degree difference from outside to inside, what you are looking for is an outlier number that would indicate a hot spot. I'd say 230 degrees, sustained, hot, you should start thinking about it. (that's with Pirellis or Contis). It's vitally important to get those numbers as the car come off the track, and they are almost as important as the pressure numbers, once you get a setup figured out, their usefulness diminishes in favor of pressure numbers. This means your in lap must be almost as fast as a race lap BTW.
In any case, figure out how much pressure your tires pick up, start the day with a cool pressure less that number (minus 1 psi)
In other words, your tires pick up 10 psi and the hot target is...35psi
Start the day at 26 psi....then come in and add or bleed off to get that 35 psi target (it's easier to bleed off)

 

[Flyboygsxr]

Did I miss what size R888 you're running? Something else to factor in is the tire width to rim width. If the tire is too wide for the rim this could also play a factor. The R888's run pretty wide so if you're running a 305 for example on an 18x10" it may not be the optimal size. I ran 18x10.5's when I had a 295 R888 on my Boss.

 

[jpt3]

What are your spring rates, what kind of shocks and what bars are you using, I'm assuming it's a Boss 302..correct?
IMO you can't hardly run enough camber in the front of a mustang.
Let me expound on that, what these guys are saying is true, you need to measure temps across the tread surface, now, take that with a grain of salt, because our tires run..about a 50 degree difference from outside to inside, what you are looking for is an outlier number that would indicate a hot spot. I'd say 230 degrees, sustained, hot, you should start thinking about it. (that's with Pirellis or Contis). It's vitally important to get those numbers as the car come off the track, and they are almost as important as the pressure numbers, once you get a setup figured out, their usefulness diminishes in favor of pressure numbers. This means your in lap must be almost as fast as a race lap BTW.
In any case, figure out how much pressure your tires pick up, start the day with a cool pressure less that number (minus 1 psi)
In other words, your tires pick up 10 psi and the hot target is...35psi
Start the day at 26 psi....then come in and add or bleed off to get that 35 psi target (it's easier to bleed off)

Thanks for the input. Here are the answers to your questions.

13 GT
200 lb front 175 rear springs rate
Stock sways now but looking at the whiteline
Adjustable. Thoughts?
I like how you broke it down for what to look for once it's figured out

 

[jpt3]

Did I miss what size R888 you're running? Something else to factor in is the tire width to rim width. If the tire is too wide for the rim this could also play a factor. The R888's run pretty wide so if you're running a 305 for example on an 18x10" it may not be the optimal size. I ran 18x10.5's when I had a 295 R888 on my Boss.

I have the team dynamics 18x10 and the tires are 295/30/18. Do you think that's part of it? How did your 10.5's look?

 

[Flyboygsxr]

In my opinion, looking at the picture you posted you would be better off with a wider rim like 10.5-11". If you go on tirerack.com you will see they recommend a 10-11" rim for the 295. Also, the measured rim width is 10.5" and the tread width is 11.2". You're losing over an inch of tread width because you're on a 10" wheel. You can see where the tread rolls over because the tire is a little too wide for the wheel so your not getting the use of the ouster edges of the tread. When I look at the wheels and tires on my GT350 the tire is slightly stretched on the rim I believe because it promotes sharper handling and less of a "squishy" feel because of sidewall deflection. You're fine to continue running the tire on those rims but you won't take advantage of all the available mechanical grip and you won't have optimal tire wear. Hope that helps

Adam

http://www.tirerack.com/tires/tires.jsp?tireMake=Toyo&tireModel=Proxes+R888&sidewall=Blackwall&partnum=93YR8R888XL&tab=Sizes

 

[Fabman]

In my opinion, looking at the picture you posted you would be better off with a wider rim like 10.5-11". If you go on tirerack.com you will see they recommend a 10-11" rim for the 295. Also, the measured rim width is 10.5" and the tread width is 11.2". You're losing over an inch of tread width because you're on a 10" wheel. You can see where the tread rolls over because the tire is a little too wide for the wheel so your not getting the use of the ouster edges of the tread. When I look at the wheels and tires on my GT350 the tire is slightly stretched on the rim I believe because it promotes sharper handling and less of a "squishy" feel because of sidewall deflection. You're fine to continue running the tire on those rims but you won't take advantage of all the available mechanical grip and you won't have optimal tire wear. Hope that helps

Adam

http://www.tirerack.com/tires/tires.jsp?tireMake=Toyo&tireModel=Proxes+R888&sidewall=Blackwall&partnum=93YR8R888XL&tab=Sizes

 

[jpt3]

Makes sense. It seems a lot people are running a 10" wide wheel when running square. What tire size are you guys running. Especially if you are running the pirelli dh mentioned earlier as I'm thinking of running that next year.

Jake

 

[Fabman]

Makes sense. It seems a lot people are running a 10" wide wheel when running square. What tire size are you guys running. Especially if you are running the pirelli dh mentioned earlier as I'm thinking of running that next year.

Jake

I'm on 10's (only because I don't have 11's)
The 295/30/18 Hoosier R7's I have been running have a cantilevered sidewall, so they are made to run on a 10" wheel.
You might look into those if a DOT slick is in your program.
In summery, you are better off to run a tire that is slightly narrow for the rim rather than a tire that is slightly too wide for the rim. Reasons have been discussed above. ^^^

 

[Fabman]

http://www.tirerack.com/tires/tires.jsp?tireMake=Hoosier&tireModel=R7&sidewall=Blackwall&partnum=93ZR8R7&tab=Sizes


They are definitely more expensive and don't last as long, but boy are they fast....

 

[jpt3]

http://www.tirerack.com/tires/tires.jsp?tireMake=Hoosier&tireModel=R7&sidewall=Blackwall&partnum=93ZR8R7&tab=Sizes


They are definitely more expensive and don't last as long, but boy are they fast....

Perhaps I'll look around on the take off market. I was told the 305 Perrelli slicks are more likes 295. Can anyone comment on that?

 

[F.D. Sako]

Consider the Nitto NT01s. I run 275/40/18s and I know they have 275/35/18s. I went with the 40 series sidewall to not run out of revs, which seems like it's you've ran into as well.

 

[Flyboygsxr]

Perhaps I'll look around on the take off market. I was told the 305 Perrelli slicks are more likes 295. Can anyone comment on that?

Yes, the Pirelli 305's are more narrow than the R888 295's. When I did a comparison I want to say they were closer to the NT01 285. I ran the Pirelli slicks on my 18x10's so you would be fine going that route, plus you can rotate to make the tires last longer. If I'm running a 2 day HPDE I will rotate after the first day in an "X Pattern". For example the front right would be rotated to the rear left. Hope that makes sense.

Adam

 

[jpt3]

Consider the Nitto NT01s. I run 275/40/18s and I know they have 275/35/18s. I went with the 40 series sidewall to not run out of revs, which seems like it's you've ran into as well.

I actually would like a few more revs. I found with these I wanted more on both tracks I've run.

 

[jpt3]

Yes, the Pirelli 305's are more narrow than the R888 295's. When I did a comparison I want to say they were closer to the NT01 285. I ran the Pirelli slicks on my 18x10's so you would be fine going that route, plus you can rotate to make the tires last longer. If I'm running a 2 day HPDE I will rotate after the first day in an "X Pattern". For example the front right would be rotated to the rear left. Hope that makes sense.

Adam

It does make sense. I think costwise it makes more sense to go take offs next time as opposed to r compounds.

Thanks

 

[Flyboygsxr]

One of the best characteristics of the R888 is they are very predictable. They are easy to slide and don't just "let go", they allow you to hold some decent slip angles.

 

[blacksheep-1]

Thanks for the input. Here are the answers to your questions.

13 GT
200 lb front 175 rear springs rate
Stock sways now but looking at the whiteline
Adjustable. Thoughts?
I like how you broke it down for what to look for once it's figured out

OK, we're running close to 500 up front and 350 in the back, Ford Racing makes a great T2 "kit" to race that class, I don't recall what the springs are however. You might want to look into that.
All the camber we can get (including cutting into the shock towers where legal)
the Ford Racing "blue bar" is a great choice for the front and the 18mm or no bar in the rear
This is on Pirelli race rubber 305/660(?)/18 all the way around, so we're getting a lot more "bite" than street rubber, and the tire rolls a whole lot more, you can do what the dragster guys do and paint "stripes" on the sidewall to see how far the car leans over, and then you'll have a better idea on camber. We've done that ourselves. We also use at least a 10 inch wheel.
A lot of guys run a lot of star wars stuff on the car, but we use the panhard bar and stock attachment points, (we do however spend around $10K on the Penske shocks.) but that's not a necessity for a street/track car.
That's kind of the standard..general..rule of thumb how to get started kind of thing. That will get you close, also the Ford Racing adjustable shocks are a pretty good bargain if you want to upgrade.

 

[Fabman]

OK, we're running close to 500 up front and 350 in the back, Ford Racing makes a great T2 "kit" to race that class, I don't recall what the springs are however. You might want to look into that.
All the camber we can get (including cutting into the shock towers where legal)
the Ford Racing "blue bar" is a great choice for the front and the 18mm or no bar in the rear
This is on Pirelli race rubber 305/660(?)/18 all the way around, so we're getting a lot more "bite" than street rubber, and the tire rolls a whole lot more, you can do what the dragster guys do and paint "stripes" on the sidewall to see how far the car leans over, and then you'll have a better idea on camber. We've done that ourselves. We also use at least a 10 inch wheel.
A lot of guys run a lot of star wars stuff on the car, but we use the panhard bar and stock attachment points, (we do however spend around $10K on the Penske shocks.) but that's not a necessity for a street/track car.
That's kind of the standard..general..rule of thumb how to get started kind of thing. That will get you close, also the Ford Racing adjustable shocks are a pretty good bargain if you want to upgrade.

Boy this information would have been great about a year ago. This is pretty much where I am now spring/bar wise but it took me a minute to sort it out and finally get there. Could have saved me all that headache hahaha.

 

[jpt3]

One of the best characteristics of the R888 is they are very predictable. They are easy to slide and don't just "let go", they allow you to hold some decent slip angles.

I've only run them for three days but my last day I was really getting a feel for them and it got very predictable in rotating the car with the throttle and sliding very nicely!!! I've heard the slicks are not as predictable. What have you found with the perelli??


Sent from my iPhone using Tapatalk

 

[jpt3]

OK, we're running close to 500 up front and 350 in the back, Ford Racing makes a great T2 "kit" to race that class, I don't recall what the springs are however. You might want to look into that.
All the camber we can get (including cutting into the shock towers where legal)
the Ford Racing "blue bar" is a great choice for the front and the 18mm or no bar in the rear
This is on Pirelli race rubber 305/660(?)/18 all the way around, so we're getting a lot more "bite" than street rubber, and the tire rolls a whole lot more, you can do what the dragster guys do and paint "stripes" on the sidewall to see how far the car leans over, and then you'll have a better idea on camber. We've done that ourselves. We also use at least a 10 inch wheel.
A lot of guys run a lot of star wars stuff on the car, but we use the panhard bar and stock attachment points, (we do however spend around $10K on the Penske shocks.) but that's not a necessity for a street/track car.
That's kind of the standard..general..rule of thumb how to get started kind of thing. That will get you close, also the Ford Racing adjustable shocks are a pretty good bargain if you want to upgrade.

It's interesting you like no sway in the rear. My car rolls so much!!! Here's a few photos what could I do? Also in reference to the spring rates. How do stiffer springs affect camber here I would think that stiffer would give you less camber in a turn because it doesn't compress as much.

 

[blacksheep-1]

It's interesting you like no sway in the rear. My car rolls so much!!! Here's a few photos what could I do? Also in reference to the spring rates. How do stiffer springs affect camber here I would think that stiffer would give you less camber in a turn because it doesn't compress as much.

That's not roll...this is roll... (I guess) on a front engine, nose heavy car, you basically give up the center of the corner a little so you can get on the gas earlier, so to give the car forward bite you run a lot of roll. To do that you have to get those rear tires planted. You also want to keep the nose supported , basically , you have to play to the car's strengths, which isn't the center of the corner. It's getting in, and getting out. The last pic (with the 275 x18 continentals, looks a lot like your car, and you can plainly see the "piano wire" rear bar.