First event on R compounds

[PunkST]

In 2 weeks Valencia and I will be hitting our areas first autocross of the season. And like the title states first one on really sticky rubber. I'll put results here when they happen. But for now what would be a good starting pressure to work with to get a feel for the tires. On my summers I ran 36 front and 50 rear to get rotation.

 

[Woods247]

I don't run R compound tires, I use RT615K which I really like. I run 31psi cold in all four and they consistently heat to 39 front 36 rear. I've never considered running the pressures you speak of because I haven't had trouble with the car rotating. What's your suspension setup? Edit: My bad, you're discussing AutoX. I'm thinking HPDE. AutoX drivers will need to chime in. 50psi on a road course sounds like a disaster.

 

[Plainrt]

Hey guy. Not sure on your ? But will see you at wir for that event. What else did you do to your car? I went back to stock class

 

[codestp202]

In 2 weeks Valencia and I will be hitting our areas first autocross of the season. And like the title states first one on really sticky rubber. I'll put results here when they happen. But for now what would be a good starting pressure to work with to get a feel for the tires. On my summers I ran 36 front and 50 rear to get rotation.

How is that pressure working for you? Never thought about doing that for autox.

 

[M-Sport fan]

When you say "R compound" do you mean the 100 tread wear class (NT-01s, Toyo R888/888Rs/RA-1s, etc.), or the various PURE race, slick/semi-slick 00-80 tread wear gumballs (R1s, all the Hoosiers, Ventus slicks, Hankook slicks, Trofeo Rs, etc.)?

 

[PunkST]

They are used advan ao48 tires and close to wear bars already so I got them super cheap, lol. Car is 99% stock. Just a mountune rear mount, a boomba bov spacer, and soon a green drop in filter. The rear pressures worked well on the courses I managed to hit last season. On an autocross the rear tires on a fwd do nothing but hold the car up. Having them super stiff from air pressure lets the inside rear slip easier if it's even touching the ground. At least that's my theory. Makes for easier lift throttle oversteer . And yes RT. It was me, ????

Just looking for experience from other autocrossers that have run very sticky tires.

 

[Solort]

Check the 4 digit stamped code on sidewall for the manufactured week and year for age to see how fresh they are. Yes, tire adhesion has a gradual pressure curve for adhesion like a roller coaster hill. Goes up till you hit a peak than they have a sharp decline in adhesion due to smaller contact patch from high pressure. I like to go with lower pressures in rear to get the rotation by softer side wall. Seems to loose rear grip more gradually vs more of a snap overseer from the really high pressures.

But the tires will be fun. Enjoy.

 

[awwwww_shift]

They are used advan ao48 tires and close to wear bars already so I got them super cheap, lol. Car is 99% stock. Just a mountune rear mount, a boomba bov spacer, and soon a green drop in filter. The rear pressures worked well on the courses I managed to hit last season. On an autocross the rear tires on a fwd do nothing but hold the car up. Having them super stiff from air pressure lets the inside rear slip easier if it's even touching the ground. At least that's my theory. Makes for easier lift throttle oversteer . And yes RT. It was me, ????

Just looking for experience from other autocrossers that have run very sticky tires.

TBH, there's 2 schools of thought on rear pressures for FWD cars.. High pressure lets them break away quicker, but when they start to slip, they snap out. On some chassis, that's a good thing(my old neon LOVED this). Lower pressure lets the tire work up until it slips away, then it breaks away more gradually.(the EF civics work better this way).

Last year on my friends car, we were 36-38ish front(depending on course, 16s or 17s, and ambient temps), and 45'ish rear. Then again, the car had konis and the titanium front bar.

For the r-compounds, I'd probably start at a level pressure(maybe stock door pressure plus 3-4) and see what the car likes. Depending on the heat cycling of the tires and the remaining compound life, that will determine dropping or adding.

If you feel like the car needs more rotation, maybe a rear beam brace and RSB are in order for you. That or a pair of konis in the back to stiffen things up may help as well.

Good luck this weekend. Id be running on sunday in MKE if it wasn't easter...

 

[PunkST]

Thanks shift. I'll need it.

 

[Plainrt]

I'd have no problem with you running in stock class with your mods. Maybe ask the others like Ben if he would be cool with it. My buddy also picked up a fist and will be running stock class. I can't wait to run in stock this year vs stx.

 

[PunkST]

She has a couple more mods now. And smf is fine with me,

 

[Plainrt]

She has a couple more mods now. And smf is fine with me,

Just other day you posted had mount, bov, filter and tires. I figured that was all. If that was case it's not a big deal to me if ran in stock. More the better lol.

 

[PunkST]

It's what it's got. Lol. Either way I need the throttle therapy.

 

[tiggerbren]

I'd have no problem with you running in stock class with your mods. Maybe ask the others like Ben if he would be cool with it. My buddy also picked up a fist and will be running stock class. I can't wait to run in stock this year vs stx.

A few weeks ago was my region's first event and my first autox ever. I put my stock intake back on to run in stock, but after seeing the results I decided to run STX for the rest of the season. There just aren't very many drivers in my region and from what I can tell I'd be just as competitive running STX and I'd get to play around some mods I'm interested in.

The week before the first event they held an autox school for the novices like myself. I was running bald falken azensis and, though I did well, the car was super squirrelly. Tons of wheel spin and the back end was super slide happy. Lot's of fun in that state. For the event the following week I had my brand new Federal rs-rr's installed and it was almost a different car. Wheel spin was under control and the back end more predictable.

 

[ericr]

Check the 4 digit stamped code on sidewall for the manufactured week and year for age to see how fresh they are. Yes, tire adhesion has a gradual pressure curve for adhesion like a roller coaster hill. Goes up till you hit a peak than they have a sharp decline in adhesion due to smaller contact patch from high pressure. I like to go with lower pressures in rear to get the rotation by softer side wall. Seems to loose rear grip more gradually vs more of a snap overseer from the really high pressures.

But the tires will be fun. Enjoy.

I agree. For HPDE, I found that with my Yoko AD08r's, optimal grip was at 35 front, 33 rear HOT.

 

[2fast]

As of now, i'm Running re71r's and don't have any scientific reasons for the tire pressures i'm running. The car is stock minus wheels and rubber.

Front 38psi HOT
Rear 45psi HOT

On my old Mazdaspeed3 chassis i needed 50psi rear to get the feel i wanted. in the fiesta this was too much. 45 seems to be the magic number on grippy surfaces. I am running a sealed surface next weekend that might require lower rear pressures.

I pick the front pressure based solely of sidewall roll. 38 brings me to right around the top of the triangle.

I was 2nd and 3rd in pax last weekend.

 

[Plainrt]

As of now, i'm Running re71r's and don't have any scientific reasons for the tire pressures i'm running. The car is stock minus wheels and rubber.

Front 38psi HOT
Rear 45psi HOT

On my old Mazdaspeed3 chassis i needed 50psi rear to get the feel i wanted. in the fiesta this was too much. 45 seems to be the magic number on grippy surfaces. I am running a sealed surface next weekend that might require lower rear pressures.

I pick the front pressure based solely of sidewall roll. 38 brings me to right around the top of the triangle.

I was 2nd and 3rd in pax last weekend.

Last year I ran like 35 front and 38 rear on re71r's for autocross

 

[2fast]

Last year I ran like 35 front and 38 rear on re71r's for autocross

have you done any testing between those pressures and higher and lower pressures to come to said conclusion? or purely based on feel?

 

[M-Sport fan]

I agree. For HPDE, I found that with my Yoko AD08r's, optimal grip was at 35 front, 33 rear HOT.

Do you also run these Yoks on the street in the summer, or are they on dedicated, track only wheels??

I ask because I am considering these for future use as a summer tire, and want to know just how horribly they wear on the street.

I just ordered a set of the RS-RRs, which in the 215/40-17 size are less than HALF of the CO$T of the Neovas, so if they burn up really fast during summer street use, it's not as big of a loss..

The 215/40-17 AD08Rs, and the Star Specs were the only other tires I was considering for the 17x8 1.2s.

 

[Plainrt]

have you done any testing between those pressures and higher and lower pressures to come to said conclusion? or purely based on feel?

Little of everything was done when autocrossing. The re71r's didn't seem picky about psi vs the 1.5s I'm running this year.