New to Evo's but not to autocross.

What is a good starting point for tire pressure on 245/35/18 Kumho V710's?

Thanks

Jim H.
DFW, Texas

 

Check out this link. Good info on pressures.

https://www.evolutionm.net/forums/sh...ad.php?t=57489

I run my Victoracers @ Front 43 Rear 48. Note that those are cold pressures.

With this setup I get some oversteer but not too much to make it "squirly". I have found that any less difference in F/R and the car understeers.

If you have great car control go with 10lbs. difference...

Good luck

 

I read the thread but not all the way thru. I just reread all of it.

I like your idea of 5-10 lbs difference to get rid of the push.

I autocrossed the car on street tires 2 weeks ago and did not like the push. I have since done an alignment (suspension is still stock but not for long) and a rear bar as well as the 710's on 18x8.5 SSR's.

I'll start with your recommended 5 lbs difference and will probably go to the 10 lbs difference to see how it feels. After driving RWD (note my screen name--gotta figure out how to change it) cars I like oversteer to get a car to rotate.

And if Mark D. says go with this front/rear difference that is good enough for me!

Thanks for the advice. I'll let you know how it works after the Sunday event.

Jim H.
DFW, Texas

 

I have good luck running my 710 with 34 psi front and keep it there every run. That seems to give me the max grip. I run 45 psi in the rear to give me some rotation. So far so good. Oh, and get a water sprayer to keep them cool between runs, they don't like heat. My starting pt is 35psi front and rear, have fun with them.

 

Looks like I now have two different recommendations to try. I'll try both and see what makes the driver and the pyrometer happy.

Ran 710's before and I already have a water sprayer. You're right, they don't like too much heat and it gets really hot in Texas. Supposed to be 98+ this weekend for my first time out on the Evo with 710's.

Thanks

Jim H.
DFW, Texas

 

I tried 36 F and 46 R first. Guess my car control isn't that good. After more testing I settled in on 36 F and 43 rear. The pyrometer and the driver were both happy and the car was rotating perfectly.

There was a sharp off-boost left at the finish that was eating everyone's lunch and with the above pressures I actually got some over steer and the car rotated nicely.

The STI guys were asking me how I did that. I did not tell them.

Thanks for all the help guys. I would have never arrived at these pressures.

Jim H.

 

My friends and I have been running higher fronts than rears (47f - 42r) all year
at auto-x events!

 

Interesting ideas. I run my RA-1's at 39F 36R HOT and I adjust after every run...I prefer a very stable setup with no oversteer or understeer.

 

Is there a best answer to the pressure qusetion for the V710 ?

Any help is appreciated.

 

There is no "best" answer. Your final numbers will be based on your car's specific suspension setup and alignment as well as grip levels on the particular lot you run, how you drive and how you like your car to feel. So just take some of these suggestions and see how it goes.

 

On the edge of the tread is a little triangle on the sidewall where it meets the tread of the tire. What you want it the wear after a run to just touch the triangle.

If the wear does not come out far enough to touch then either you have extreme camber angles, or too high a tire presure.

If you have tire wear that has scrubbed the triangle itself, then your tire presures are too low.

That's what I try to do anyway. With my v710s (275/40/17) I run them between 29-33 depending on weather conditions and the surface I run on.

I generally try to keep a 1-2 psi difference between the front and rear to balence the car for the course.

 

Wow, 29-33 seems very, very low. It's quite interesting how vastly different everyone's pressures are...

 

yeah, it has taken a little getting used to. But that is what the tire wear and pyrometer is telling me to do.

To add to my other post, start with higher presures and work your way down to where you are comfortable with how the car.

Judging by screen name I am sure you already know that...

 

I ran A3S05 Hoosier's last year and settled in at 52f/58r (yes, pretty crazy but the S05's were a strange tire). I'm running V710's this year and from the posts will probably start around 45f/50r and go from there. I think tire pressure is very car setup specific and driver specific, so I never have had a problem with telling people my tire pressures.

 

That's fine if you have an LSD, but the 03 and early 04s don't so they understeer like crazy (higher rear pressures help the car rotate).