Here's the issue...

Running 225/50/16 Kumho V710's on all 4 corners of my new 2006 Civic LX (6.5" width) for H Stock autocrossing. Alignment is set with toe out on all 4 corners, and the OEM Honda camber bolts are installed up front (Koni's aren't available yet)...

In 80* heat, the car sticks like glue (too well in fact) to the point that it doesn't understeer, but it doesn't rotate well either and that's with 38 - 40 psi up front and 60 psi rear! Wheelspin is not an issue up front btw.

I was wondering, I am limited in size options to fit my wheel width range, however, I saw the old Ecsta V700 or even the Ecsta MX is available in sizes small enough to possibly allow for better rotation...

Kumho Ecsta V710 225/50 WR16 (Currently Front and Rear Tire Choice)

TREAD DEPTH: 4/32"
TIRE WEIGHT: 24 lbs.
RIM RANGE: 6-8"
TEST MEASURE: 7"
SECTION WIDTH: 9.1"
TREAD WIDTH: 9"
OVERALL DIA.: 24.7"


Kumho Ecsta V700 205/45 VR16 (**Possible Rear** Tire Choice)

TREAD DEPTH: 6/32"
TIRE WEIGHT: 19 lbs.
RIM RANGE: 6.5-7.5"
TEST MEASURE: 7"
SECTION WIDTH: 8.1"
TREAD WIDTH: 7.6"
OVERALL DIA.: 23"

Kumho Ecsta MX 205/55 WR16

TREAD DEPTH: 9/32" (I'd have them shaved so that it's dia would equal the V710)
WEIGHT: 21 lbs.
RIM RANGE: 5.5-7.5"
TEST MEASURE: 6.5"
SECTION WIDTH: 8.5"
TREAD WIDTH: NA
OVERALL DIA.: 25.1" (Shaving would get this to within .2" of the V710)


Opinions on feasibility? Or do you think even an OTS Koni Sport (when available) will aid rotation enough that I should be able to still use the same size tire at all 4 corners?

Thanks...


Modified by honda93 at 10:57 PM 4/16/2006

 

Hmm, never heard of a fwd honda not understeering!

What are your camber specs?

I like the MX, but I found it to be more of a DD tire, probably a tire under your skill level.

Btw, what size of rim are you runnning? (width)


Modified by carbnjunkie at 1:05 AM 4/17/2006

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by carbnjunkie &raquo;</TD></TR><TR><TD CLASS="quote">What are your camber specs?

Btw, what size of rim are you runnning? (width)</TD></TR></TABLE>

After speaking with someone about it and thinking it over a little longer, I'll just keep the 4 same size tire setup and dial in more toe out. But if you must know...

CAMBER

About -1.0* ~ -1.4* Front (OEM camber bolts maxed out)

About -1.4 ~ -1.5 Rear (non-adjustable)


TOE

FRONT: -1/8 total toe out

REAR: -1/16 total toe out (I'll probably go to -1/8 total)

 

The first thing I see is you're running way too much pressure. I'm getting mine down to the teens or low 20's without rolling over. But that still doesn't totally explain why your rear end doesn't want to rotate. Not that it must either.
How were your times? If the car felt great as is (besides the pressures) why do you want to change anything?
I have always done the more pressure up front thing and it seems to work better for me than the more pressure in the rear thing for rotation.

Your tires can't possibly be rolling over at 38+ psi.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dvp &raquo;</TD></TR><TR><TD CLASS="quote">The first thing I see is you're running way too much pressure. I'm getting mine down to the teens or low 20's without rolling over. But that still doesn't totally explain why your rear end doesn't want to rotate. Not that it must either.
How were your times? If the car felt great as is (besides the pressures) why do you want to change anything?
I have always done the more pressure up front thing and it seems to work better for me than the more pressure in the rear thing for rotation.

Your tires can't possibly be rolling over at 38+ psi.</TD></TR></TABLE>

I disagee. All tires are different, so they can be rolling over at 38 psi. That is not a irregualar steup for most FWD cars, and I for one run almost 48 cold in back and 42 in front during my runs.


Modified by carbnjunkie at 3:25 PM 4/17/2006

 

For a long time I did the high pressure in the rear to attempt to get it to rotate. It works, but I never found it to work that well.

I'd try lowering your rear pressure to the high 20's or low 30's.

Generally, I have found rotation is better when the rear tires are low as opposed to very high.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by carbnjunkie &raquo;</TD></TR><TR><TD CLASS="quote">I disagee. All tires are different, so they can be rolling over at 38 psi. That is not a irregualar steup for most FWD cars, and I for one run almost 48 cold in back and 42 in front during my runs.


Modified by carbnjunkie at 3:25 PM 4/17/2006</TD></TR></TABLE>

Yes, all tires are different however we are talking about the same tire here. Although mine are 13" for my wheels.
I don't know how you're possibly using the whole tire with that much pressure. The very first time I ran the 710's I ran them at 35 front 32 rear and I was still 3/8" away from the corner of the tire. Thus me going down in pressure till the corner is touching.
Are you actually rolling over with anything under 38psi??

 

This is just my .02 and some will disagree with it but it's free advice so you get what you pay for.

The V710's seem like a great choice for either all 4 or just the fronts. Regarding the 60 psi rear pressure, I realize that it is partly a driver preference issue but I think there are better ways to achieve what you want. You are asking the front and rear tires to do very different things. Up front you want maximum traction with stability and quick steering response, i.e. low slip angles, all things that the 710 you listed will do. I agree with others that even your front pressure seems a bit high. In the rear it would be better to have higher slip angles and a more progressive and controllable breakaway than you can get with ~60 psi pressures. That can be achieved by using a tire with a narrower tread, a softer sidewall, a taller profile, and lower pressures, or some combination thereof. I don't know if any of the current crop of R compound tires have what would be considered a truly "soft" sidewall but I think the MX would be in that relative ballpark. Again, I know this is largely driver preference and style, but consider trying fairly low pressures in the rear that will allow the contact patch to *twist* instead of using really high pressures to make the rear tires *skate*.

 

i agree. although i have no experience with those tires or an 06 lx, i have had 5 hondas. i autox with 45psi front and 35-38psi rear. 22mm sway helps too. i dont see the reasoning in your tire pressure setup

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dvp &raquo;</TD></TR><TR><TD CLASS="quote">Are you actually rolling over with anything under 38psi??</TD></TR></TABLE>

No, but it is near the edge.... Remember this is a bone stock car with no shocks (until Koni produces something) and relatively soft springs. The sway bar up front isn't all that stiff at 25mm and hollow, but I don't want to go further (using the Si 28mm solid front unit).


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nello a. &raquo;</TD></TR><TR><TD CLASS="quote">i agree. although i have no experience with those tires or an 06 lx, i have had 5 hondas. i autox with 45psi front and 35-38psi rear. 22mm sway helps too. i dont see the reasoning in your tire pressure setup</TD></TR></TABLE>

But were any of them run in Stock? As for the rear sway bar, I am limited to what came on my LX Coupe from the factory with a small 11mm unit!!! I'll never have killer rotation with that kind of bar. SUre, I wish Stock allowed this, because I loved the 22mm rear bar I had on my 93 Coupe.

But rules are rules.

I will try lowering the pressures both front (35psi) and rear (30psi) this wwekend and give a follow up. Thanks everyone!

 

Agreed with tjbizzo (good free advice there). The point of overinflating your rears is to get them to bow out and not stick, and therefore break traction early. I have a bone stock car (94 Prelude) that I race in GS, and I use 4lbs lower pressure in the rear.

I've never run R tires, but I think your problem is that they're so sticky, they just won't break free even with the overinflated effect. However, if you run them about 30psi, I can guarantee you they will rotate faster without breaking traction. Low rear pressure is about playing with slip angles, not about drifting.

Dan

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by honda93 &raquo;</TD></TR><TR><TD CLASS="quote">the car sticks like glue (too well in fact) to the point that it doesn't understeer, but it doesn't rotate well either </TD></TR></TABLE>

I don't mean any disrespect by it but this sounds like you're not charging hard enough.

This year I started experimenting with different tires front to rear to get more oversteer. Right now I'm running V710 front and V700 rear (same tire sizes) and getting a whole lot more oversteer than before. So far I really like the results and plan to continue this settup for a while.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LudemanDan &raquo;</TD></TR><TR><TD CLASS="quote">Agreed with tjbizzo (good free advice there). The point of overinflating your rears is to get them to bow out and not stick, and therefore break traction early. I have a bone stock car (94 Prelude) that I race in GS, and I use 4lbs lower pressure in the rear.
Dan</TD></TR></TABLE>


I'll experiment with lower pressures out back than up front. Thnaks.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RineRacing &raquo;</TD></TR><TR><TD CLASS="quote">I don't mean any disrespect by it but this sounds like you're not charging hard enough.</TD></TR></TABLE>

Maybe in 1994 when I started autocrossing that would have been correct.

 

I'm curious now. If a car isn't understeering, I would try to carry more speed through the turn. At some point I would try to carry too much speed and the car would start to push.

So, in your car, when you drive and the car doesn't understeer what happens if you try to take a turn a little faster?

 

One side will eventually break free before the other side.