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Old 05-02-2004, 02:29 AM   #1
sajohnson
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Default Goodyear GS-D3 Soft Sidewall Issues

I just replaced Firestone SZ-50 EP's with GS-D3's.

The Goodyears are great in wet conditions and have a decent ride quality but seem to have more vague turn-in and transient response. They are also more susceptible to cross-winds, and do not hold a line as well in corners.

Anyone else notice this?
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Old 05-02-2004, 05:53 PM   #2
NegativeC
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I think the crosswind thing is just that it's been a little more windy recently , although I have noticed the other things also to a small extent. I think the V tread doesn't allow as much contact patch surface area as some other designs but is great for wet conditions and spirited day to day driving. What size and pressures are you running? My 225/50/16's were rolling over a bit at an AutoX event at 42PSI but 45 PSI seemed to be the sweet spot. This helped a lot with the sidewall stiffness too and performed very well at that point.

They are a Max Performance tire for sure and handle better than 99% of the tires out there. However if you are AutoXing on a regular basis you may want something with a stiffer side wall for those fast transitions, plus you could save a bit of $ too.

I still love mine as they aren't as loud or harsh as some others but still offer a ton of grip and believe they are fully worthy of a
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Old 05-02-2004, 07:58 PM   #3
sajohnson
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Dude! 45 psi?! Is that all the way around?

That may be alright for an auto-x event but for a daily driver it seems a bit much.

I've tried up to 41 psi in the front with 35 or 36 psi in the rear, but with that much pressure the ride was really harsh, and I'm running the stock suspension and tire size. It seemed like I had reached the point of diminishing returns as far as the ride/handling trade-off.

Right now I'm running 39 psi front/33 psi rear.

I typically ran the SZ-50 EP's (and my previous tires, B/S RE730's) at 37/32, an they were noticeably crisper handling. At least that's my recollection, but I'll be the first to admit that my memory isn't great. Also, another factor is that the SZ-50 EP's were about at the wear bars, so they were at their best in the dry right before I took them off.

I think you're rigth about the tread pattern on the GS-D3's not putting as much rubber on the road. Also, it seems to me that while the tread on the shoulder seems rather solid, the sweeping center design seems prone to lateral movement under stress.
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Old 05-03-2004, 10:27 AM   #4
Gonz
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Default Re: Goodyear GS-D3 Soft Sidewall Issues

Quote:
Originally posted by sajohnson
I just replaced Firestone SZ-50 EP's with GS-D3's.

I think part of what you are feeling is the tread squirm from having a tire with a lot of tread on it ( new ) compared to a tire you just replaced.

I would agree that the sidewall is somewhat soft, at least when running 225-50 on stock rim as I too am doing. For me, going up to 33 PSI front and 31 rear is plenty for street driving.

On the autoX, I found that 38 PSI was enough to keep the front tires from rolling over ( found this by marking the shoulder with white shoe polish)

I do have springs and Konis on the car which maybe helps keep the pressures down a bit. I also have about 15,000 miles on them and they do have noticeably less tread than they had when new.

I think it is not the best tread design for autocross as the tread blocks are really narrow and can feather a bit under abuse, but for $50 less per tire than th Bridgestone S03 and fantastic wet traction, they are pretty nice.


Gonz.
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Old 05-03-2004, 10:42 AM   #5
SlideWRX
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I switched from S-03's, and noticed the turn in is a little less precise. I really don't mind, as the quieter, softer ride with a lot less tramlining sold me. I do 35F 33R psi on 225/45R17. It may be the difference between new tires & worn, but either way I like these better.

Tom
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Old 05-07-2004, 10:42 PM   #6
sajohnson
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Thanks for the replies.

I've noticed something else -- when the tires are warm and I drive over some fine dust or pollen, it sticks to the tread and shows the approximate width of the contact patch.

With 39 psi front and 33 psi rear, contact patch in front is still wider than that in the rear, and the front tires are also rolling onto their sidewalls a bit (compared to the rear).

It seems like I should add a few psi in the front, but I am reluctant to do so because the ride will be really harsh and I am concerned about wearing out the center of the tread.

I was actually considering reducing the pressure in the rear by a couple more psi to widen the contact patch a bit. As it is, it appears that about 1" of tread on either side of the tire is not making contact. Is this normal? 33 psi is not much over stock (29 psi).

As I mentioned above, I typically ran both of my previous sets of tires at about 37/32 and they wore perfectly evenly across the tread.

Comments, suggestions, complaints?!
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Old 05-09-2004, 01:25 AM   #7
sajohnson
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Default Ideal Pressure?

I adjusted the air pressure to 38.5 psi front and 30.5 psi rear.

This seems very close to the ideal pressure for the street. The handling is much more neutral and secure feeling.

Last edited by sajohnson; 05-12-2004 at 07:54 PM.
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Old 05-13-2004, 10:43 PM   #8
sajohnson
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2002 WRX 5MT Sedan
WR Blue. Cobb Stage 2

Default Roll Triangles

While asking around about how to determine proper tire pressure, I was told to use the 'roll triangles' molded into the sidewall just below the shoulder of the tread.

The idea is that during hard cornering, the tire should roll over just enough so that the tip of this triangle makes contact with the pavement.

Has anyone heard of this?

In my experience, if I used this roll triangle method, the pressures would be close to stock and the handling would be very sloppy, especially with the Eagle F1 GS-D3's.
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