Report No. 2 on Dunlop 205-60-15 tires:
I think I may be the only one running theses tires so far, at least the only
one talking about them. The tire is slightly shorter than the Hoosiers and a
little wider. I get a minor "hot rub" that has burned the paint on the
"apex" of the stock fender flare in teh front. The Hoosiers also did this.
My lap times are a little slower than the Hoosiers, but I think there is a
lot more in the tires than I've found.
May 17th.: Conditions ranged from 70 to 80 degrees and, slight breeze and
sunny all weekend (it doesn't get any prettier anywhere, anytime). I set out
with the goal of setting the pressures to attain an even temp across the
tires, and front to back. Neither was accomplished.
15 min qualifier, out at 22 FT and 21 RR, in 28 LF, 27.5 RF & 25 LR, 25.5 RR
15 min race, set at 21.5 LF/22RF/22LR-RR, in 28LF, 27.5 RF & 25.5 LR, 26 RR
20 min race, set at 22 LF/22.5RF/23LR-RR, in 28.5LF, 27.5 RF & 27 LR, 27.5
RR
Raising the pressures in the rear did not change the relative temp.
relationship with the center. Both inside and outside temps remained 4 to 8
degrees cooler than the middle. This is the same as what I got when I ran
31.5 psi in both rears in April. Accordingly, I think I need to drop the
rear pressures even more. The problem is that the fronts are quite a bit
hotter than the rears (max 162 to 139). I didn't change the front much
because they were close to what I was looking for. I started with a slightly
hotter inside of the tires and cooler outside compared to the center and
adding or dropping a 1/2 pound didn't change that relationship. In April I
ran at 32 psi up front and had 9 to 15 degree drop off to either side.
Again the conclusion I have come to is lower the pressures even more. I
think I have the camber right as I am 2-3 degrees from inside to center. I
would appreciate any advice on this as the advice from the seller, Roger
Kraus, was pressures in the 28-32 psi range. My lap times did not improve at
all over the weekend and I'm wondering what to try next.
Bob Kramer
rkramer3@austin.rr.com
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: "'Bob Kramer'" <rgk@flash.net>
Cc: <fot@autox.team.net>
Sent: Monday, May 19, 2003 3:31 PM
Subject: RE: Dunlop tires
> So how did you like the tires? Are they Radials? What static camber are
> you at? I'd be looking for the middle temperature to be close to either
> the inside or outside edge, whichever is hotter. Your inside edge should
> naturally be hotter because it gets better cooling and if you have
> sufficient negative camber it's the edge that does all the heavy lifting
> down the straights.
>
> As I recently learned the hard way, you don't want to set camber by tire
> temperature unless you've got a skidpad or a track with no appreciable
> straights. But you can trust tire temperature to tell when you're
> over/under inflated.
>
> All the same, if they are radials they will tend to like a lot of
> camber--like 3 to 4 degrees. You'll corner well in the high-g turns,
> though not in the fiddly stuff and your lower rolling resistance down the
> straight will give higher top speed. I've found high camber increases
> understeer in slow turns and decreases it in fast turns. I don't know why.
>
>
> I'm trying to sort out what I'm learning accounting for the differences
> between my high-downforce Radical on slicks and minimal downforce Peyote
> on treaded Hoosiers.
>
> -----Original Message-----
> From: Bob Kramer [mailto:rgk@flash.net]
> Sent: Monday, May 19, 2003 12:21 PM
> To: Bill Babcock
> Subject: Dunlop tires
>
>
> Bill,
> Took your advice and ran the tires up from 20 pounds. By the end of the
> weekend I wasn't able to determine the perfect pressure setting but I was
> up to 24 in the rears and 22.5 LF and 23RF. I packed up the pyrometer
> early and didn't get the temps for the last session, but I was getting
> closer to even temps in the front, around 160. The rears lagged at around
> 145 but were moving closer to even. more work to be done. My lap times
> didn't change appreciable, but I was fighting a stumbling problem which
> appears to be electrical, and the throttle shafts breaking didn't help
> any. The advice was sound and helped. Thanks, Bob
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