johnc Posted May 9, 2005 Share Posted May 9, 2005 A good review for those that may not remember all that's involved with the care and feeding of race tires: https://www.hoosiertire.com/rrtire.htm Quote Link to comment Share on other sites More sharing options...
2126 Posted May 10, 2005 Share Posted May 10, 2005 Hey John, my tires are certainly not race tires (good read) but I feed my Yokohamas back-top! If I try to feed them too quickly they complain a little, but I think they like it! Thanks for the post. Quote Link to comment Share on other sites More sharing options...
260DET Posted May 10, 2005 Share Posted May 10, 2005 Bugger feeding and caring for them, mine won't get hot and sticky so no treats for them No seriously, the Kumho Victoracers in 225 50 15 on 8" rims on my S30 just won't heat up over a few laps. Cold pressure has been progressively reduced down to 23 psi but after a few laps they are barely warm, even with some sliding around. My theory is that that the car is now so nicely set up and with the tyres sitting well on the 8" rims that there is just not enough stress and distortion being put into the tyres to warm them up. Plus summer has gone although its far from cold. Is this a characteristic of these Kumho's? Suggestions? Hope that I haven't hijacked the topic, seemed extravagant to start another. 1 Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted May 10, 2005 Share Posted May 10, 2005 260DET, your either not driving hard enough or have a bad pyrometer. Your tire is not that big. You've really got to use the slip angles to generate heat. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 10, 2005 Author Share Posted May 10, 2005 I ran the exact tires you have when my 240Z was in its previous configuration. Typical tires temps at an autocross were 150 to 160 and the V700s felt good. Typical tire temps at a race track were 180 to 200 and they felt very good at 180 and greasy at 200. As said above, if you're driving the car hard enough you should be seeing temps in those ranges. Check your pyrometer and be sure to use the probe type, not the infrared guns. Quote Link to comment Share on other sites More sharing options...
260DET Posted May 11, 2005 Share Posted May 11, 2005 Thanks Clarkspeed and John. Going to drop the cold pressure down to 21 at the front, the rears heat up quicker, but no lower in case the tyre wants to roll off the rim. Have been sliding it around a bit to warm the tyres up, but the front just washes out when cold. Perhaps a bit more than 1mm toe out will help the fronts warm up quicker. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted May 11, 2005 Share Posted May 11, 2005 front washes out-need smaller front sway bar.if car is too stiff it wont bite.i have no problems heating up 225/50-15 kumho v700's.probably wouldnt be my choice for a race tire but since i only screw around with open track days and driver's schools it is the best bang for the buck.try more negative -like 3 to 4 degrees -camber.most race cars these day use stiff springs with little or no sway bar.a well sorted street z on kumho's should be able to outrun slower classes of trailer queens-i have done it. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 11, 2005 Author Share Posted May 11, 2005 Normal race or street alignment settings shouldn't have have a significant affect on tire temperatures. Maybe how you're taking tire temps is a reason they are so low? Is there a long straight just before pit in? Are you taking the temps in the hot pits? Are you having to get out of the car to take the temps? FYI... the lowest I've ever run the V700s was 25 psi cold. Any lower and the tires didn't respond well and felt floppy. And if you're driving the car right the rear tire temps should be a bit higher then the fronts. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 12, 2005 Author Share Posted May 12, 2005 In the latest issue of Welding Journal (published by the American Welding Society) is a comparison of infrared temperature measuring guns and direct contact temperature measuring devices. In all cases the guns read below the test material's controlled temperature. In some cases the guns read over 400 degrees low (aluminum plate) due to the reflectivity of the surface. The direct contact measuring devices were well within 1% of the test material's controlled temperature. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted May 12, 2005 Share Posted May 12, 2005 Be VERY careful running a DOT race tire below 28psi. Again, it's not going to put more heat in. I've found the Kumho's like 35-38. Quote Link to comment Share on other sites More sharing options...
260DET Posted May 12, 2005 Share Posted May 12, 2005 Its all very peculiar. Discussed it with the supplier and he said that Kuhmo recommend hot pressures way higher, high 30's, than he and others have found best. A friend of mine has found 23 cold best in his Exctas on a Triumph TR8 and he's quite methodical about such things. The other day mine were barely warm to the touch across the tread, in contrast with the Dunlops and Toyos used in the past which you couldn't bear to touch, let alone keep your hand on at all. This is all in sprint events, three to five hot laps of a circuit. Oh well, we'll see how it goes on the 'home' track in a couple of weeks time, hopefully the sun will be out and the black stuff hot Quote Link to comment Share on other sites More sharing options...
johnc Posted May 12, 2005 Author Share Posted May 12, 2005 A lot of the DOT-R tire manufacturer's tire temperature recommendations are based on a stock vehicle's suspension geometry. When you can get 3 degrees negative camber you can lower the recommended tire pressures. Again, tire temps are the best indicators of proper tire pressure. BTW... I just noticed my link above was wrong, here's the direct link: https://www.hoosiertire.com/Tctips.htm Sorry... 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.