col Posted June 21, 2006 Share Posted June 21, 2006 Hi i agree with most of what john is saying even with road tyres ,an even temp means even tyre wear ,f you have a tyre capable of more girp why not use it.Sure good times can be got with a really wide tyre working on one side but it is capable of even better times using the whole tyre.Road tyres ,while not like slicks, still need to get to temp,lower pressure more heat simple as that. As far as stiff sidewalls i agree stiff is good for 2 main reasons ,they have less flex and this lets us run lower pressure for more heat, but still let you increace pres if they get too hot. Many years ago i raced a xu1 style torana ,I had no money and everything was on a budget ,so we did what we could with normal street tyres .everything was seat of the pants,we had thin sidewals ,so we would stretch195 tyres on 9" rims and played with pressures to get the best compromise between grip and flex.Doing this can teach how important tyre pressure is.but back to the first string wide soft tyres can be great on the road dry but over wide tyres no matter how soft will be bad in the wet. col Quote Link to comment Share on other sites More sharing options...
tube80z Posted June 22, 2006 Share Posted June 22, 2006 Even temps across the tread does not *necessarily* imply the quickest setup. No direct experience meself (not nearly consistent enough to make a judgment, and besides, I'm lazy. I just run conservatively high pressures) but at least one successful 240Z race effort found they had quicker lap times with higher temps on the inside of the tread. Tire sizes were somewhat skinnier than 275, though I have direct experience with my car and hotter on the inside is what is generally required. How much hotter depends on the tire characteristics and toe can have an effect as well. What you're really looking is to have the tire optimized when cornering, which leads to the higher inner temps when measured at the end of a run. In the Motec seminar Claude shared IR tire temp data that showed surface temps during a lap and you could see this. What we measure is well off what the tire sees. He even showed us examples where we would have done the completely wrong thing based on pyrometer data we'd measure in the pits. It also became pretty damn clear that if you're doing any serious racing or chassis development you must have this level of data or you will be working in the dark. Cary Quote Link to comment Share on other sites More sharing options...
Wiisass Posted June 22, 2006 Share Posted June 22, 2006 John, those tire temps don't really say much. I mean if your saying that what you ran there was the best setup where the comparison data? Do you have temp data and lap times for running the tires at 40psi hot? Like Cary was saying, I think that measuring tire temps over the course of a lap will just tell you if your setup is close to what it should be for the course. I mean if your inside temps are 50degrees hotter than the outside, then your going to have to adjust something. But if they're in a good range, then you should be fine. IR temps are something that would really help out with suspension tuning, but most people don't have access to stuff like this and the cost on it does add up pretty quickly so it's not for the less serious. But knowing the temp on the surface of the tire during a run at each part of the course will give you a much better idea than measuring temps at the end of the lap. you do have to keep in mind that surface temps don't correlate in any linear relationship with core temps, so the IR temps are essentially measuring something different than core temps. John, another question, are you provided with tire curves for the tires you run? I mean they suggest a pressure based on these curves and what their testing shows. Quote Link to comment Share on other sites More sharing options...
col Posted June 22, 2006 Share Posted June 22, 2006 Hi I think we have changed this thread a lot. I understood the question was about street tyres not slicks on cars runing huge camber setings.stiff walled slicks with heaps of camber puting the tyre in full contact with the road through corners when you need the traction they ,scrub the inside in a straight line puting more heat on the inside even after a hot lap driving into the pits the inside will be kept a bit hoter .If we are talking about road tyres on a road car with less camber the temp's should be much more even.If your road tyres get that much hotter on the inside you are going to have uneven wear problems. col Quote Link to comment Share on other sites More sharing options...
johnc Posted June 22, 2006 Share Posted June 22, 2006 John, those tire temps don't really say much. I mean if your saying that what you ran there was the best setup where the comparison data? Do you have temp data and lap times for running the tires at 40psi hot? Lap times were off by at least 1 second when the Hoosiers were at or above 40 psi hot and the car was very skatey. Dropping pressures got us better and more consistent lap times and then we started tuning with temps. The temps when running 40 psi hot or above were cooler then what I listed above. Hoosier recommended tire temps "around" 200 as an indication that their tires were working properly. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.