Hey all,<p>I spent the day yesterday (in 110 degree heat indexes) out at Blackhawk Farms (Rockton, Illinois) for the Quattro Club School. They had about 65 cars entered in the school, and there were some gorgeous A4's out there.<p>One thing I did notice, and this may be a case of a lack of individual thought, but like every A4 out there was using the Bridgestone SO-2 Pole Position as their track tires. Now, for an all around tire, I realize that this is an awesome tire, but for these guys who all changed wheels to track and race setups, what is the point? Aren't R1's, Hoosiers and Yokahama track tires available in 16 and 17" sizes for the A4? <p>I would much rather have a set of sticky, shaved race tires on 17" BBS RC's than a new fresh set of SO-2's. Is there something I'm not aware of about Quattros? Or was this simply a case of follow the leader?<p>Are there any track guys out here on the list? What hae you done to the brakes to avoid fading, warping and boiling of fluids?<p><p>-doug

I have taken my car on about 15 autox days this past 1.5 years...and about 10 track days (Quattro Club, SCCA Street School, and NASA). I have been on track with the 205/55/16 Conti-Tourings....the 205/55/16 Dunlop 8000Es....the 225/45/17 P7000SS...the 225/45/17 Dunlop SP9000...and the 225/50/16 BFG R1 g-force "track tires". Obviously, the R1s performed the best. They lasted almost a whole season of autox and track endeavours. Next time will I get them?...probably not...I think I will go for the less expensive...and longer wearing Kumho Victor Racer 700s...I think they are about $130/tire in 225/50/16 size. I really like the idea of driving the Kumho's to the track...rather than putting track tires on the car AT the track.<p>As far as brakes go...when I changed to the rofren brake pads (only in front) and went with the OEM size Brembo cross drilled rotors..I did not get brake fade. I also make sure to bleed my brakes about every 6 months....I had ATE Super Blue Racing fluid in my car...but the dealer thought it was dirty stock fluid...and they "did me a favor" by replacing it with the stock yellow stuff. Oh goodie! The super blue helped prevent overflow situations when the fluid expands or boils. Super Blue has a slightly higher boiling point....and mine never boiled over. My rotors are not warped...nor show that much wear.<p>Hope this helps.<p>Steve S.<br>97 2.8QM

Hell yeah! Thanks for the experience, Steve. Jamie mentioned that you spent a lot of time on the track with your car and that you would be a really great source of information. I was just teasing abou the A4 forums on the VWvortex side, too. :)<p>I am going to replace the stock rotors with Brembo cross drilled, even will all of the claims of "exploding and cracking" rotors from cross drilling. Brembo makes top shelf products and I'm not worried about the quality. I'm going to match them with the Carbotech Super Street pads, and Ate Super Blue fluid.<p>I'm not sure what I will do about tires, though. The stock loud and crappy Dunlops are on their last legs and beg to be beaten on. I'm planning on doing numerous track days and schools with this car next summer, and I'll probably do some lightweight racing wheels with sticky race tires for the track, but for the street, I'm still undecided. The thought of driving the Chicago winters in a Quattro with Hakkapeliitta Hakka 1's, is still quite appealing. Ohhhh, snow.<p>Thanks again for the info, Steve. See you in Monterey.<p>-doug

I use ATE Super Blue, and it still boils over =(<p>Warren

Really? That stuff is DOT 5! Wow. That's impressive.<p>Apparently, the Ford over-the-counter brake fluid is some of the best stuff on the market, at only about $3 a pint.

I don't think I brake hard enough....crap....I gotta work on that.<p>Steve S.<br>97 2.8QM

Actually I was at Summit Point in West Virginia. There are 2 hard braking zones. It's harder on the brakes than Texas World Speedway.<p>Warren

My friend and I went to a "CarGuys" school at Summit Point and he managed to burn almost an entire set of pads in one weekend on his Integra. My Prelude faired only a little better. Ouch!<p>-- David F.<br>1.8TqMS<br>E30 325is

I am trying to figure out effective final drive ratios with different tire combinations<p>For example, here's my 96 A4Q 2.8 tech data<br>Final Drive ratio is 3:20 to 1<p>Assuming a PERFECTLY ROUND stock wheel as reference of 205/55/16 here are the effective final ratios using different popular tire sizes for the A4: (and a few more just for kicks as program setup in excel)<br>205/55/16 = 3.20 (overall dia. = 24.88 inches)<p>18" wheel<br>225/40/18 = 3.17 (overall dia = 25.09 in)<p>17" wheel<br>205/50/17 = 3.18 (overall dia = 25.07 in)<br>215/45/17 = 3.23 (overall dia = 24.62 in)<br>215/40/17 = 3.35 (overall dia = 23.77 in) LOW RIDER he he he<br>225/45/17 = 3.19 (overall dia = 24.97 in)<br>235/45/17 = 3.14 (overall dia = 25.32 in)<br>235/40/17 = 3.26 (overall dia = 24.40 in)<p>16" wheel<br>225/50/16 = 3.20 (overall dia = 24.86 in)<br>225/45/16 = 3.32 (overall dia = 23.92 in)<br>225/40/16 = 3.45 (overall dia = 23.08 in) ULTIMATE LOW Rider<p>Ok, that's enough fun.<br>My question,<p>With each aspect ratio, does anyone know the effective wheel radius? <br>Reason being for a higher profile tire, the side walls have a tendency to sag more so, the effective diameter is shorter which makes it easier to turn the stock 205/55/16 wheel vs a 225/45/17 if both have the same weight.<p>Looking at my A4Q specs, for example top speed for each gear is at least 2mph slower than my calculations using a perfectly round wheel. This observation makes me assume that the 205/55/16 side wall is at 96.6% of it's height due to sagging. For a 40 series tire, sagging is even less and the actual side wall height gets closer to 100%.<p>Any ideas? Or am I fooling myself?<p>My goal is to achieve a good drive ratio for different track events. For example, I could use a smaller wheel at Sears Point instead of my 225/40/18's because the track is pretty technical and acceleration at corners is my goal. So I am planning to put 225/45/16's on my stock rims. Any thoughts?<br>

Have a lot of spare time?<br>Your formula is correct, in an ideal world. Tire sizes are largely nominal, particularly R tires. So a p9000 vs. a hoosier of the same 225/50/16 bear no real similarities in dimension, except for the 16" inner hole (and even there the hoosier is .5" smaller).<p>You idea for gearing down is fine, particulary in 16" with the extra sidewall to begin with. Mind you the actual desired gearing may not reflect the tire change. Typically, gearing is set to redline at the end of the longest straight. This gives you the fastest time (not really, but close enough). First is so low that we can barely use it. <p>If the course is really twisty go for a drop.

I don't think you will feel any significant difference.<p>Steve S.<br>97 2.8QM

I played with a ¼ mile program I found from the web which I would say is pretty accurate. I entered what I know about my A4 so far like gear ratios, hp and torque numbers, F/R ratio, AWD, weight, height, etc…<p>I used 2000 ft elevation and my personal shift points of 1-2 at 5800rpm, 2-3 of 5600 rpm. I always launch my car at 4000 rpm and this program agrees with me somehow. Shift time is 0.2 sec (ya right!)<p>Things that I need to add to make it more accurate are coef of drag, frontal area, drive train frictional losses, other things, but at least I got what I needed - approximate differences in ¼ mile times.<p>Tire loaded 0-60 ¼ mile effective<br> dia. (sec) (sec) final drive<br>225/40/18 24.2 8.12 15.967 3.17<br>235/45/18 25.4 8.18 16.011 3.02<br> <br>205/50/17 24.2 8.15 15.994 3.17<br>215/45/17 23.8 8.12 15.969 3.02<br>215/40/17 22.9 8.21 15.939 3.35<br>225/45/17 24.1 8.13 15.977 3.19<br>235/45/17 24.4 8.14 15.981 3.15<br>235/40/17 23.5 8.09 15.943 3.27<br> <br>205/55/16 24.0 8.16 15.999 3.20<br>225/55/16 24.8 8.17 16.011 3.10<br>225/50/16 24.0 8.14 15.986 3.20<br>225/45/16 23.1 8.31 15.952 3.32<br>225/40/16 22.3 8.01 15.928 3.44<p>Here's Steve's tire inquiry<br>245/45/16 23.8 8.12 15.965 3.23<p>Notice that with a effective final drive of 3.3? the 0-60 times are longer. In reality, the 0-60 time for a 225/45/16 is 8.12 sec. However, the 2-3 shift happens at 60.001 mph, so, the program takes the time in third gear. But ¼ time is the best.<p>I think I found my wheel for Sear's point or Auto-X - Saving money by using my stock rims, I'll try 225/45/16's. Other than that, stick with my costlier (3x more) 225/40/18's ouch!<br>

I added it in posting below. I don't think it will fit in our 16x7's though. Sounds like a good size wheel

<br>I played with a ¼ mile program I found from the web which I would say is pretty accurate. I entered<br>what I know about my A4 so far like gear ratios, hp and torque numbers, F/R ratio, AWD, weight,<br>height, etc…<p>I used 2000 ft elevation and my personal shift points of 1-2 at 5800rpm, 2-3 of 5600 rpm. I always<br>launch my car at 4000 rpm and this program agrees with me somehow. Shift time is 0.2 sec (ya<br>right!)<p>Things that I need to add to make it more accurate are coef of drag, frontal area, drive train<br>frictional losses, other things, but at least I got what I needed - approximate differences in ¼ mile<br>times.<p>Tire loaded 0-60 ¼ mile effective<br> dameter (sec) (sec) final drive<br>225/40/18 24.2 8.12 15.967 3.17<br>235/45/18 25.4 8.18 16.011 3.02<p>205/50/17 24.2 8.15 15.994 3.17<br>215/45/17 23.8 8.12 15.969 3.02<br>215/40/17 22.9 8.21 15.939 3.35<br>225/45/17 24.1 8.13 15.977 3.19<br>235/45/17 24.4 8.14 15.981 3.15<br>235/40/17 23.5 8.09 15.943 3.27<p>205/55/16 24.0 8.16 15.999 3.20<br>225/55/16 24.8 8.17 16.011 3.10<br>225/50/16 24.0 8.14 15.986 3.20<br>225/45/16 23.1 8.31 15.952 3.32<br>225/40/16 22.3 8.01 15.928 3.44<p>Here's Steve's tire inquiry<br>245/45/16 23.8 8.12 15.965 3.23<p>Notice that with a effective final drive of 3.3? the 0-60 times are longer. In reality, the 0-60 time for a<br>225/45/16 is 8.12 sec. However, the 2-3 shift happens at 60.001 mph, so, the program takes the<br>time in third gear. But ¼ time is the better determinator.<p>I think I found my wheel for Sear's point or Auto-X - Saving money by using my stock rims, I'll try<br>225/45/16's. Other than that, stick with my costlier (3x more) 225/40/18's ouch!<br>

I've had numerous boiling fluid problems at the track with my 94 S4 (big car with small brakes). After trying numerous fluids (including Pentosin "racing only" fluid - big $) I now only use the standard Ford over the counter fluid. It costs about US$4 a can from any Ford dealer.<p>This is the only fluid I have never had a problem with, it is dirt cheap, and gives a good pedal feel. Dry boiling point = 550F.<p>I know a number of guys who run and swear by Ford fluid in their competition race cars.<p>Dwayne<br>94 S4