I did my first DE on the RA-1s yesterday, it was a blast! I was wondering what kind of tire pressures I should be running in them. I guessed and had them at 34 cold. I kept forgetting to test them after I came back in though so I dont have any 'hot' numbers.

Also, although the tires gripped wonderfully, I sensed that they felt a little squirmy. Is this normal for full tread RA-1s? Theyre 255/40s on 17x8.5 wheels.

 

From what I've read, that's normal when full tread. If you didn't shave them, then they won't really get grippy until you've used them several times. They continue to get better and better the more they wear until they suddenly cord and you need new ones.

 

Right around 40 hot is good. Team up with someone in a different run group and crew for each other so you can get hot pressures and temperatures on the pit lane. Ideally you want to pull off during the session rather than waiting for the cool-down lap. Depending on the weather and track, 34 cold is likely too high, especially in the front. If you can really make use of XP-10s you should be keeping good tire data!

Dave

 

38 hot is ideal, don't go off cold pressures

 

38-40 hot, sticker tires will squirm a bit your first session or two on them, once they wear a bit it goes away, especially under breaking, after a couple heat cycles they get far far far easier to "feel" if you know what I mean.

Scorke

 

Alright, so Ill shoot for 38-40 hot. I need to write myself a note or something, Im always so pumped up when I come in after a session that I dont think about checking pressures.

 

i was running 35 / 38 hots, and robi said i should run some more pressure in them. I'm gonna give it a whirl, but when i had them up near that before they were SUPER squirmy.

yeah, my cold pressures when i got done...

27/23.5 (front)
31/28.5 (rear)

can ya tell it was a counter clockwise track?

 

yup, 38-40 hot is where you wanna be.

n

 

all around? (remember, stock suspension here)

 

Yup, tire's dont know what they are attached too .

Scorke

 

yeah, but in running what i was, i was still pushing a good deal. At 40 psi, i'll still be pushing like a mad man. I was running 35-35 most of the day, then was bumping a pound a session in the rear, and it was helping, probably 35-40 would have been the best.

At those kinda pressures, i'll be kinda bouncy too.

The more air in the tires, the less flexing the tires do = the more they leave the pavement = the less traction i have.

Unless i'm misunderstanding something. Homestead and Sebring are not pristine pieces of pavement

 

I dont think 5 psi especially whilst in the 35-40psi range has much of an effect if any on contact patch, I could be wrong though. If by pushing you mean understeer than you should of probably been adding air to the fronts and dropping some from the rear, I believe....

Scorke

 

What about temps?... should they be around 180-200 degrees? If a rear tire is colder should you take some PSI out until it comes up to 180? Those with pirometers... chime in

 

https://www.evolutionm.net/features/...vomfeatures/46

Sometimes, stuff really is right under your nose hahah!!!!! I didn't know evom already had this up, but it seems everything is explained in there, king kyle you seem to be dead on with ur temps. Again I could be wrong but I think you want to add pressure if your temps are not getting high enough....

Scorke

 

incorrect.

Adding air decreases the contact patch, therefore decreasing grip.

My issue now is simply camber, and stock suspension, which is unchangable currently.

The car was drastically different from 35/35 to 35/38, and this weekend i'll keep adding to the rears, and probably bump all the pressures up 2 psi or so, per robi's suggestion.

Since it was pushing, you'd normally let air outta the fronts, but i wasn't gonna run them any lower, so the other option, is add to the rears.