Bridgestone SO3's

[Steve Red '92]

Just put 4 S03's on the car and I'm very pleased with the grip and wet weather traction. The dealer set the alignment to '93+ spec.'s (4mm rear toe) and did a front alignment as well.
The steering now feels a lot different, much lighter, easier to turn at low speeds but when you go fast, 80MPH + , the steering feels vague when you are going in a straight line.The car doesn't have the same on-center feel. With the OEM Yoko's it felt so glued to the road and confidence inspiring.
I have about 200 miles on the new tires so it may be a little early to tell.
Anybody have any thoughts? Did the dealer mess up the front alignment or is this a characteristic of the tire?
Any way to get the original feel of the car back?
Appreciate any help you can offer.

 

[docjohn]

the oem tires were designed with a degree of natural scrub due to the directional tread patern.To reproduce this with so3's is tough.I run with 91 spec alignment and dont get the crisp feeling.If you toe in, the car will want to go straight, toe out and it will get twitchy,and want to turn ,so you'll just have to play with it a bit.

 

[pacman]

I have a 1991 (chassis #74 which I have owned since new). This is my third year tracking the car (stock other than wheels). For this year I have changed to BBS LM wheels (17 x 7.5 F; 18 x 9.0 R) and mounted SO3s. I have done 5 track days plus highway driving (about 3,500 km total) since the new tires were mounted, 3 days at Mosport and 2 days at Watkins Glen. They look like new. Last year on the Yokos (15F, 16R) I only got 3,500 km out of a set of rears. I had an alignment and changed the rear toe-in to 93+ spec. It made all the difference in the world. Next I am installing Porterfield R4S pads.

 

[docjohn]

you may want to rethink the porterfield r4s.I was disapointed with there short life and tendency to crumble.They are reletively inexpensive though.I did better with rm pads and i hear good things with the panther line.pagid and hawk are great but I think you need big breaks to fit these.

 

[sjs]

Originally posted by pacman:
I have a 1991 (chassis #74 which I have owned since new). This is my third year tracking the car (stock other than wheels). For this year I have changed to BBS LM wheels (17 x 7.5 F; 18 x 9.0 R) and mounted SO3s. I have done 5 track days plus highway driving (about 3,500 km total) since the new tires were mounted, 3 days at Mosport and 2 days at Watkins Glen. They look like new. Last year on the Yokos (15F, 16R) I only got 3,500 km out of a set of rears. I had an alignment and changed the rear toe-in to 93+ spec. It made all the difference in the world. Next I am installing Porterfield R4S pads.

OK, but with your track experience you should be a great person to tell us how OEM vs. SO3 compare in lap times, which is what I'm really curious to hear about.

I recently put SO3s on my '93, using 2002 OEM sizes. Unfortunately I have had very little opportunity to drive it hard and not at all on the track since then so I can't say for sure about max cornering.

However, the vague on-center feel at speed is a given since they lack the built-in scrub of OEM tires. (Actually the carcass and belt design, not just the tread) You can improve it by switching to toe-in, but then you sacrifice how it turns in. I keep the stock toe settings.

 

[pacman]

My track days in 2002 have been in sanctioned events that banned timing. However, I carry higher speed into corners because they corner much better (eg terminal speed going into corner 8 at Mosport - the fastest track point)has gone up from 180 km/h to 210 km/h. The extra inch of rubber helps too. We will see how the Porterfields work this weekend which should aid corner entry speed. Straight line feel is fine. I haven't had any rain days yet this year - which is where I have noticed the R toe-in the most in the past. The 17/18 wheels with the 255/40 R tires may lose a bit of low end acceleration out of tight corners (they are 4.7% larger) but they look great. Some say the 16/17 wheels with the SO3s are better. Oh well!

 

[Steve Red '92]

To update everyone, I change the front to -2.0 mm and the car is MUCH improved. The stabilty at high speed is back and I haven't noticed any change in the turn in.

The camber and castor are stock front and rear.
Front toe is now -2.0mm
Rear toe is +4.0 mm

The next time I take it in I'll get them to reduce the front toe a little more, I think it can get even better. I'll keep you updated.

My recommendation for tire replacements is the SO3 P.P. with front toe -2.0mm or less

Thanks for the replies I got, they helped a lot.