hey guys,
Bought the toyo t1-r's and they came 36 psi all around but I bumped the front to 39 to compensate for the weight in the front being more. Today I did my usual backroad spirited driving and going no faster than usual my back end gave out (oversteer right?) my cars front end went to the inside of the turn and I did a 180 and stopped. Is oversteer caused by not having enough pressure in the back tires/too much in the front? I'm pretty shook up from this experience as I've owned my evo for 2 years and have never experienced anything like that so any ideas on the oversteer would be helpful thanks

-kyle

 

Well, there a few points:

1) New tires are slick, they need to be broken in before they give proper adhesion. So if you went hauling *** as you did on the advans, I am not at all surprised that you spun out.
2) The Toyo T1-R are not as sticky as the advans. So if you went hauling *** as you did on the advans, I am not at all surprised that you spun out.
3) You can play with tire pressures too, but other factors can influence things too (alignemtns; throttle lift for example). I suggest reading this:

http://www.tirerack.com/tires/tirete....jsp?techid=58 and
http://www.turnfast.com/tech_handlin...pressure.shtml

in short:

Adjustments Decrease Understeer Decrease Oversteer
Front Tire Pressure Higher Lower
Rear Tire Pressure Lower Higher

Good Luck

 

thanks but ya I've already put about 1100 miles on these tires so its not the new factors..I actually did this loop a couple days ago before i adjusted the tire pressure and my tires didnt give out but they squealed a lot more..I realize the advans are stickier but I was definitely going slower in comparison to when i had the advans I was just comparing to the other day with these same tires..chances are it was just driver error on my part (too much gas before I was exiting the turn but it happened so quick I cant really be sure) but I wanted to make sure the tire pressures didnt influence the cars will to almost kill me haha thanks again

 

yes.

to increase oversteer: raise front psi / decrease rear psi
to increase understeer: lower front psi / raise rear psi

 

+1

http://www.club4ag.com/faq%20and%20t...mendations.htm

Good reference material. Worth an Internet bookmark...

 

first off whoever said ra-1's are less sticky than the stock advans have obviously never been on a track.
don't get me wrong, the stock are a great "street" tire but still give up 2-3 seconds per lap easy
on a road course.
your problem isn't tire pressures. the real problem here is tire temps. stocks don't really need
to get up to a specific operating temp to get to full grip levels. the avans do get some benefit
from heat as do any hi-performance street tire.

the ra-1's do(any r-compound for that matter) need heat to get to their real grip level. so if you
just run up a canyon on cold tires you will get oversteer much easier until they warm up.

 

Toyo T1-R's and RA-1's are different tires, so that doesn't really apply.

-Paul

 

sorry man i really should have read that closer.
my bad
i guess i should get checked out for dyslexia

 

Since you are driving this stretch of road all the time, you can make this your 'tuning' track. Play with the tire pressure and see what happens. Adjust up or down and feel how the car behaves. I always start with 35 all around and then adjust.
The ambient temperature when you are running, was it hot or cold? Was the road sandy or dirty at the time?
Do you have a bigger rear swaybar? that will get your rear coming around fast too!
Last, maybe you should check out a HPDE event around your area for safe training

Be safe

 

+1 on that. DE are the best place for trying out different setups. Get a good pyrometer, and measure temps all around, and pressures hot and cold, and adjust pressure to get the feeling you're looking for. Its a fun trial and error game...just make sure the errors are done safely....

 

Isn't it the other way around? Raising the tire pressure generates a similar affect as increasing spring rate. I keep my tire pressure higher and shocks stiffer in the rear to get rid of my understeering during autocrosses.

 

you can get to the same place both ways if your adjustments are extreme enough.
lower pressures enough and you roll over the corners of the sidewall=less contact patch
raise your pressures enough and you crown the center of the tire=less contact patch

 

http://www.club4ag.com/faq%20and%20...mmendations.htm

Good reference material. Worth an Internet bookmark...


Thanks HMSevo8 for the good link!

 

ya I actually went back and looked and the spot where I spun out they seem to have put some new tar down and there were some pebbles chillin there so I think i must have hit those and spun out...I still wanted to make sure that my tires were ok anyways so thanks for all the help..I'm running 39/37 front/rear right now after a little trial and error but I just dont know how to know if i'm crowning or not cuz I want them high as possible to make up for the less stiff sidewall but obviously too stiff leaves less contact patch..I guess the real (unrealistically moneywise) solution is to just stick with what i know the advans but I wanted to try these tires out..they sidewalls are mushy no matter how much psi I put in them compared to stock so I guess I just got spoiled with the old tires..Sometimes I wish the center of gravity on our cars was lower it feels like it just puts too much strain on the tires compared to a lower car...Will lower springs and a different strut or sway bar make me not hate having these tires as much and if so which ones? thanks

 

I agree, raising rear pressure will increase oversteer. Running lower pressures in front will allow more heat to be put into the front tires. On a track, the tires should be close to the same all the way around after a 20-30 minutes session. It takes time, but it's fun.