For the few of us that actually do track these things.... one thing I've always been left guessing about is tire pressures. Since I rarely run into someone else at the track running tires this small, and local shops don't know much about them, I haven't found much advice.
So for the Sport Demons (110 front, 140 rear), I can say that a few PSI lower than street has worked for me. Usually ~30 front, ~32 rear, cold. I'm probably 215lbs with gear and have .85 Sonic fronts and a kat rear shock.
"Worked" as in my one lowside was my own fault and I've only had the rear step out just a few times in ~10 events. I trail brake some and put down power pretty early without any unpredictable behavior. I am recently an intermediate rider by most groups' standards. The tires show I'm getting to the edges, seem to last at least 6 track days and they don't show signs of overheating. For me, the bike's pretty much on rails 99% of the time, so I'm content.
Please post similar information here with what you've experienced and any recommendations for figuring out when the tire pressure is right. Maybe it's better to check and set them hot? I really barely know what I'm doing. :cheers:
Don't bother posting your "canyon carving" pressure recommendations please. :icon_razz:
That was the same pressure that the Pirelle guy put on my tire after 30 minutes on track. Worked perfectly for rest of day. Fortunately we had the pirelle vendor to help us out on tire pressure. That would be where i would ask if they have vendors on your track days.
Ok, the BT 003 RS (110 front, 140 rear). Per bigjimmerone's recommendation, I should try checking them hot and keep them around 31-31.5 PSI. I started with them around 29 PSI cold and ended up bleeding out 1 or 2 through the day. They were often 32ish when I would check them. My form was far less than perfect (I was tired!) but they just stuck like glue all day and wear shows I was all the way out the edge on the rear, with just a tiny strip showing on the front. I'll probably start both ends at 28 PSI next time.
Why do we shoot for the same PSI on both ends on track when street pressures recommend higher on the rear? I have no clue. :dunno_white:
The tire vendors or suspension guys out at the track can usually give you a good ballpark to start with for the tire you're running. Odd that you've heard similar pressures front and back. M'boy and I are both running different flavors (Michelin/Pirelli) of DOT race, and the recommended pressures for both are in the low 30s front and mid-20s rear. It's good to have a gauge sitting where you pit and ready to go, and to read your tires after each session.
I use 26 in the rear and 29 in the front "cold" I usually run the Bt090's, but this last race I ran an 003 on the front with the 29 "cold" pressure. This is the pressure given to me from our tire vendor. My mechanic told me to bump the cold pressure up on both to 30/30 and my bike handled like a pig for that session. I went back to what the tire vendor told me to run after that.
If you are running the Sport Daemons you can run the rear at 30lbs, but the front you should keep at about 30lbs. The Sport Daemon fronts destroy themselves at a hard pace as the rubber is too soft and balls up really bad. I tried a variety of pressures and couldn't get the problem to go away.
BT090's are fine for trackdays but the 003's are the way to go if you really want to push it as the 090's will get greasy in about 5 hot laps.
I've used the bt090's for a 3 hour endurance race several times and had no problems with them. My home track is bumpy as all get out but not abrasive. I've gotten two or three race weekends out of a set of 90's with no problem, as long as I am not teaching a race school. If so, I heat cycle them to death and they just feel like rocks at that point but as long as I am not pushing very hard they are still ok...The 003's are a definite step up but I would not hesitate to continue to race the 90's if I couldn't get my hands on the 003!
I talked to a budy of mine who used to race these back in the day and is a wholesaler for dunlop, he said 34 front and rear cold, but he has been out of the game for awhile
Forgive me for resurrecting an old thread.
I'm racing on BT003RS this season. Dave Moss (of Catalyst Reactions) recommended 23PSI in the rear tire, and 26PSI in the front. Those pressures were confirmed by the bridgestone rep at AFM round1 in buttonwillow. Ideally, I'm looking for about a 3-5PSI temperature rise, tested immediately after returning to the pits from race pace.
So far, this setup has been working very well for me. The tires pass a subjective 'hand to rubber' temperature test, and have been gripping well. The tires are showing excellent wear.
Suspension is .85 springs up front, with racetech emulators, 20 weight oil, stock sag, and 120mm fluid level. Rear shock is a 01 Katana 750 bolt on. Not sure of the exact settings - dave adjusted it, and I never touched or inspected his settings.
Excellent tires for this bike. I'm currently running 2:16s around buttonwillow, with plenty of traction to spare.
Good on you for posting up some new info!
Good info here thanks. I'll be running BT003RS's as well this year.
Update:
I'm back from AFM round 2 at Sears Point (Infineon) raceway. My fastest lap was a 2:06, and I'm averaging 2:07-2:08 without much effort. I'm really liking these tires. Traction has been very good, and they slide very predictably.
Some problems with my lines and reference points caused me to push the front through turn 11 on a fairly regular basis. The problem went away after walking the track with a more experienced racer. The tires slid recovered gracefully. None of those slides ever caused major problems.
I would strongly advise anyone running emulators to take it very easy during the first session of the day. Both at Buttonwillow and Infineon, I've had the front end go away big-time while cresting the top of a hill (turn 6 at Buttonwillow, and turn 3a at Infineon.) In both cases, I was able to recover from the slide using my knee without any real difficulty. I attribute the slides to the fact that rebound damping is controlled by ports in the damping rod (even with emulators installed,) and that the recommended 20 weight oil is unbelievably thick in the morning, resulting in way too much rebound damping.
The front tire seems to wear more than the rear. I suspect I'll need a new front after the next race weekend, and my rear should be good through 2 more events.
Quote from: ecpreston on September 15, 2009, 11:27:58 AM
Why do we shoot for the same PSI on both ends on track when street pressures recommend higher on the rear? I have no clue. :dunno_white:
I think I know the answer. Most street riders (like me) aren't Kenny Roberts or anything approaching him. Slightly more pressure in the rear than up front would make a bike tend to understeer a little which makes a bike more forgiving, easier to ride. If you are talented, trained, and practiced, and want to cut mean corners on the track, understeer is not desirable.
I too have a track GS, and am racing tomorrow.....but it's my first time and I've forgotten what pressures to run.
So, thanks to this thread I'll start on 32, 32 and go from there. But, I don't know what I'm feeling for regarding if they're too high or low. How can I tell?
Thanks.
Running 090s