Cold? Hot off the warmers? (what kind of warmers? How long have they been on?) Hot off the track? Whats ambient temp? Is the track abrasive? Air or Nitrogen? Listen to your tire vender not the BBS!
Dear LiquidSnake, I was directed by a customer to your post and was told to help you out. I'm Quentin Mise, of Mize Mobile, the Northeast Michelin racing tire distributor. The reason you were asked if you bought those tires on ebay by a fellow WERA racer was because the PR1 front has been discontinued as a sprint racing tire for some time now. It's a good track day tire that is sold by many reputable track day clubs as a lower cost alternative, but as for actual racing we've been selling a newer tire for quite some time now. The 29 psi front and 22 psi rear recommendation you received is actually a pretty good one. We run 30-31 psi in the different racing fronts that we currently use, but the older PR1 design had a very, very stiff carcass and it "felt" better to most medium to slower riders if they dropped it to 29 pounds. The 22 psi rear is the correct cold starting point for the PR5 rear that you have, which by the way, is still a very current racing tire. It's not generally as fast as the PR3, but generally lasts longer than the 3, (I know guys, not always, flame away,,,,) but generally speaking the 5 is the tire used when the guys are looking to get a few runs out of the same tire, and the three is the one used when they want to go REALLY fast, like track record fast in many cases, but for only one, maybe two races. Some novices report that they can get three good 8 lap seesions out of a PR3. We set our pressures at "cold" or ambient temps. Then apply the warmer at around 175 deg f for 45 minutes (this is the high setting on the three position chickenhawks, and the only setting for their basic one position product) and then let the tires expand from there as they see fit. If it's really hot out, they'll expand more, same if you ride really hard. If it's colder, and/or you're slower, they'll expand less, that's ok, let them self modulate. The reason some other brands have to set pressures hot, is because they can't safely run at 22psi under some conditions, at some tracks, under some riders, they use a more flexible sidewall and therefore count on the air pressure to give structure to the tire. The Michelin rears, have a stouter sidewall, and can run lower because the air accounts for less of the structure of the tire. The windings and the weaves in the cords actually push out and give structure to the tire when the throttle is applied, so right when you load it the most, it pushes back the hardest. This is why it is safe to run our stuff much lower than almost everything else, generally speaking. There are "trick" tires that other brands have coming to the market that try to emulate this, but we've had this in our stock tires for three years now. This is not always true of our 07 spec slicks, many of them also have thin sidewalls and need more air to give "structure" so again, ask your local trackside tire rep what he does with that specific tire, to get the most up to date and safest information. If you need more help, feel free to click my ad banner that rotates with other advertisers at the top of the screen, and contact me on my site. If the MizeMobile banner doesn't show right away, just click the refresh button a few times and we'll pop up on a random basis. Good luck, thank you for choosing Michelin, and ride safely. -Quentin
Quentin, Thanks for the intel man... I am glad that you could take the time to share that with me.. I will be talking with you throught your site about this more. Thanks again to all who posted
