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914World.com _ 914World Garage _ tire pressure for Kumho V710's

Posted by: itsa914 Sep 8 2005, 01:29 PM

OK, the car is off getting the corner balance, neg camber, alignment thing done. I have the Kumho V710's mounted on the keizer rims, so what tire pressure to start with for AXing. With my Falkens I ran 38 psi, is that a good starting point or should I start lower? Higher?

Posted by: VegasRacer Sep 8 2005, 02:13 PM

Don't know about the V710's. My Victoracers did best at 31.

Posted by: sean_v8_914 Sep 8 2005, 07:28 PM

wow! 38 psi ? were they Azinis? RT 215 or new RT 615?

Posted by: trekkor Sep 8 2005, 07:58 PM

I ran my Falken's up to 39psi front and 41psi rear. ( 215's )

I am very eager to hear the pressure recommendations for the V710's too, as mine are getting installed tomorrow.

I'm sure they run at differant pressures for a/x and BIG track, right?

KT

Posted by: itsa914 Sep 8 2005, 08:36 PM

QUOTE (sean_v8_914 @ Sep 8 2005, 05:28 PM)
wow! 38 psi ? were they Azinis? RT 215 or new RT 615?

They are the RT 215.

Trekkor,

They guy at the Tire rack that installed mine said that most AXers were running at 36 - 38 PSI with the 710's

Seemed high to me for such sticky tires but then again what the heck do I know.

Posted by: Aaron Cox Sep 8 2005, 09:02 PM

QUOTE (sean_v8_914 @ Sep 8 2005, 06:28 PM)
wow! 38 psi ? were they Azinis? RT 215 or new RT 615?

i was running 39 f/r with 215's

Posted by: J P Stein Sep 8 2005, 09:39 PM

I used to run 26 in my Vracers.
I'd start at 30 & fool around with the pressures.
I'll talk to my Miata buddies & see what they run.
Most AXers don't have 2000lb cars.

Posted by: itsa914 Sep 8 2005, 09:50 PM

Thanks JP

Posted by: sean_v8_914 Sep 8 2005, 10:45 PM

I was surprised because I know 4-5 guys in PCA-SDR that start at 25 psi cold w/ RT 215 and now the RT 615. it works out to about 30 hot on short AX courses. about 32 at the DE after 20-30 min running

is that 39 hot or cold?

Posted by: trekkor Sep 8 2005, 11:15 PM

QUOTE
is that 39 hot or cold?

For a/x, set cold then let air out after each run to bring it back down to your #'s.

FYI- Hoosier's increase by 3 psi per run

KT

Posted by: KenH Sep 9 2005, 12:43 AM

Well I cannot find the thread about Kumho, but it said to set the pressure so the tire just rolled over to the "V" molded into the sidewall.

This would suggest that the pressure should be different for AX and TT as the load on the tires will also depend on speed.

The other way is to measure the tire temperature, but that has to be done in about 60 seconds after a last full speed run. Hard to do with out a "crew".

Ken

Posted by: ge9146 Sep 9 2005, 10:11 AM

Garold,

I ran 28 in front and 34 in the rear (cold) on Victoracers on my 6. They seemed to build up by just a few psi depending on the length of the run. I tried to look at the rollover and adjust for that. I will admit that I am still getting used to my car. I am not sure how the 710s would be different though. Have fun with your new set up. There is a 2 day event at the Tire Rack on Sept 17 and 18th if you are interested.

Ed Scott

Posted by: itsa914 Sep 9 2005, 10:35 AM

Thanks Ed,

Can't make the 17th ( 3 1/2 yr son has his first soccer game ) and the 18th is our local SCCA solo (aka AX)

Posted by: slow911 Sep 14 2005, 04:16 PM

Ed- I'll be there on the 17th and Garold I'll see you on the 18th......damn this season went by toooo fast....and I'm still slow....but I'm picking up a set of Hoosiers tomorrow and hopefully butr not likely will have them on by this weekend.

Brian

Posted by: trekkor Sep 25 2005, 11:59 PM

Ran the 710's at the a/x to a second place finish.

started on 27 psi front and 28 psi rear.

went to 30 front and 32 rear and shaved off a tenth in a "fun run".

Temps were 132° rear and 115° front. very similar to my heat cycle last week.

Also, the high temp was 165° rear on the track on Friday.

I'll try the pressures at the higher 30/32 next week and experiment at 34/36 and see what that does.

KT

Posted by: trekkor Sep 26 2005, 12:02 AM

I'll be curious to here how KenH liked his new 710's over the weekend at the DE/TT.

KT

Posted by: KenH Sep 26 2005, 05:05 PM

OK here's the story.

Thunderhill 2.?? mile track.

Air Temp about 85.

Started the V710s at 36 pounds COLD.

Ran 20 minute laps reducing the pressure by 2# until the tires got "slippery". (this was very noticable)

Raised the pressure back up by 2# and they stuck like glue.

With the tires cold this pressure turned out to be 28#.

Did not measure HOT temperature.

Ken

Posted by: trekkor Sep 26 2005, 08:45 PM

thanks, Ken. Nice to see you on Friday evening.

KT

Posted by: trekkor Oct 3 2005, 12:11 AM

These tires work!

30 fr 32 r. for a/x.

KT

Posted by: itsa914 Oct 3 2005, 07:53 AM

My next AX is Oct 16th I will try that pressure and see what happens. I ran the last one at 34 Front & rear, not bad but it was raining so a little slippery, that and I really need to get more neg camber